6277 + Interview Questions in Physics Page 25 InterviewSolution

1201.	Why do we classify the liquids as good conductors and poor conductors instead of conductors and insulators? Explain with an example. [3 MARKS]
Answer» Why do we classify the liquids as good conductors and poor conductors instead of conductors and insulators? Explain with an example. [3 MARKS]

Discussion

1202.	Which among the following arrangement is true regarding the speed of light?
Answer» Which among the following arrangement is true regarding the speed of light?

Discussion

1203.	the two ends of a metal rod are maintained at temperatures 100C and 110 C .The rate of the heat flowin the rod is found to be 4 J/s.If the ends are maintained at temperatures 200 C and 210 C,the rate of heat flow is?
Answer» the two ends of a metal rod are maintained at temperatures 100C and 110 C .The rate of the heat flowin the rod is found to be 4 J/s.If the ends are maintained at temperatures 200 C and 210 C,the rate of heat flow is?

Discussion

1204.	In optical fibre, refractive index of inner part is 1.68and refractive index of outer part is 1.44. Thenumerical aperture of the fibre is(1) 0.5653(2) 0.6653(3) 0.7653(4) 0.86
Answer» In optical fibre, refractive index of inner part is 1.68and refractive index of outer part is 1.44. Thenumerical aperture of the fibre is(1) 0.5653(2) 0.6653(3) 0.7653(4) 0.86

Discussion

1205.	(3) 7425 L atm(4O28. An ideal gas is allowed to expand from 5 L to 15 L once rapidly and once very slowly. The magnitude of wor(a)done in two processes are W, and W, they are related as2'(1) W, = W2(2) W, > W2C(3) W< W(4) Data is insufficient
Answer» (3) 7425 L atm(4O28. An ideal gas is allowed to expand from 5 L to 15 L once rapidly and once very slowly. The magnitude of wor(a)done in two processes are W, and W, they are related as2'(1) W, = W2(2) W, > W2C(3) W< W(4) Data is insufficient

Discussion

1206.	39. if the three vectors a, b, c are non-coplanar. express a, b, c each in terms of the vectors bc, ca, ab.
Answer» 39. if the three vectors a, b, c are non-coplanar. express a, b, c each in terms of the vectors bc, ca, ab.

Discussion

1207.	21. The difference apparent frequency of a source of sound as perceived by an observer during its approach and recession is 2% of the natural frequency of the source. The velocity of the source is [Take speed of sound in air = 300 m/s] (1) 6 m/s (2) 3 m/s (3) 1.5 m/s (4) 12 m/s
Answer» 21. The difference apparent frequency of a source of sound as perceived by an observer during its approach and recession is 2% of the natural frequency of the source. The velocity of the source is [Take speed of sound in air = 300 m/s] (1) 6 m/s (2) 3 m/s (3) 1.5 m/s (4) 12 m/s

Discussion

1208.	Rajiv connected two exactly similar heating elements (or resistances) across a mains supply in two different ways to heat some water.(a) Is more heat obtained when the heating elements are connected in series or when they are connected in parallel?(b) Give reasons for your answer.
Answer» Rajiv connected two exactly similar heating elements (or resistances) across a mains supply in two different ways to heat some water. (a) Is more heat obtained when the heating elements are connected in series or when they are connected in parallel? (b) Give reasons for your answer.

Discussion

1209.	Sound and light waves:
Answer» Sound and light waves:

Discussion

1210.	What is the difference between thermal energy and heat energy?
Answer» What is the difference between thermal energy and heat energy?

Discussion

1211.	A heavy brass sphere is hung from a weightless inelastic string and used as simple pendulum. its time period of oscillation is T. When this sphere is immersed in a non-vicious liquid of density 1/10 that of brass. If it acts as simple pendulum then find its period
Answer» A heavy brass sphere is hung from a weightless inelastic string and used as simple pendulum. its time period of oscillation is T. When this sphere is immersed in a non-vicious liquid of density 1/10 that of brass. If it acts as simple pendulum then find its period

Discussion

1212.	A particle moving in a straight line covers first half of the distance into two equal time intervals with speed of 2 m/s and 4 m/s respectively, and second half with speed of 5m/s. The average speed of the particle is
Answer» A particle moving in a straight line covers first half of the distance into two equal time intervals with speed of 2 m/s and 4 m/s respectively, and second half with speed of 5m/s. The average speed of the particle is

Discussion

1213.	the strain energy stored in a body of volume v due to shear strain
Answer» the strain energy stored in a body of volume v due to shear strain

Discussion

1214.	Question 11How many times is a ray of light reflected by two plane mirrors placed parallel and facing each other?
Answer» Question 11 How many times is a ray of light reflected by two plane mirrors placed parallel and facing each other?

1214.

Question 11How many times is a ray of light reflected by two plane mirrors placed parallel and facing each other?

Answer»

Question 11

How many times is a ray of light reflected by two plane mirrors placed parallel and facing each other?

Discussion

1215.	Given that equilibrium constant for the reaction 2so2+o2__2so3 Has a value of 278k at a particular temperature what is the equilibrium. Constant for the following reaction at the same temparaure So3____so2+12o2
Answer» Given that equilibrium constant for the reaction 2so2+o2__2so3 Has a value of 278k at a particular temperature what is the equilibrium. Constant for the following reaction at the same temparaure So3____so2+12o2

Discussion

1216.	Why does the C.N of solid decrease with the increase in temperature ?
Answer» Why does the C.N of solid decrease with the increase in temperature ?

Discussion

1217.	Using the "conduction tester" on an object it is found that the bulb begins to glow. Is that object a conductor or an insulator? Explain.
Answer» Using the "conduction tester" on an object it is found that the bulb begins to glow. Is that object a conductor or an insulator? Explain.

Discussion

1218.	ntA battery of emf 100V and a resistor of resistance 10 kilo-ohm are joined in series. This system is used as a source to supply current to an external resistance R. If R is not greater than 100 ohm, the current through it is constant up to two significant digits. Find its value.n ntn ntHc 199n
Answer» ntA battery of emf 100V and a resistor of resistance 10 kilo-ohm are joined in series. This system is used as a source to supply current to an external resistance R. If R is not greater than 100 ohm, the current through it is constant up to two significant digits. Find its value.n ntn ntHc 199n

Discussion

1219.	Two discs A and B are mounted on a vertical axle. Suppose the discs have moment of inertia as I and 2 I respectively about an axis. Disc A is given angular velocity ω, using the potential energy of a spring compressed by x 1. Similarly the potential energy of a spring compressed by x 2 gives an angular velocity of 2ω to Disc B. Considering that both the discs rotate in same direction .Find the ratio x 1/ x 2 :
Answer» Two discs A and B are mounted on a vertical axle. Suppose the discs have moment of inertia as I and 2 I respectively about an axis. Disc A is given angular velocity ω, using the potential energy of a spring compressed by x _1.Similarly the potential energy of a spring compressed by x ₂gives an angular velocity of 2ω to Disc B. Considering that both the discs rotate in same direction .Find the ratio x ₁/ x _{2 :}

Discussion

1220.	Define potential energy.
Answer» Define potential energy.

Discussion

1221.	calculate the resis†an ce if 5 ampere of electric current flows through a conductor having potential difference between two points is equal to 15 v
Answer» calculate the resis†an ce if 5 ampere of electric current flows through a conductor having potential difference between two points is equal to 15 v

Discussion

1222.	An object moved from A to B, covering a distance of 300 m at a speed of 20m/s. It then travelled from B to C, covering another 300 m in 15 seconds. Find the average speed of the object in travelling from A to C, if it stopped at B for 30 seconds.
Answer» An object moved from A to B, covering a distance of 300 m at a speed of 20m/s. It then travelled from B to C, covering another 300 m in 15 seconds. Find the average speed of the object in travelling from A to C, if it stopped at B for 30 seconds.

Discussion

1223.	Write answers to the following questions. (a) What is meant by natural resources? (b) Which are the two types of natural resources? (c) What are the uses of soil? (d) What is ‘nulla bunding’? (e) What is ‘biotechnology’? (f) What are the differences between renewable and non-renewable resources?
Answer» Write answers to the following questions. (a) What is meant by natural resources? (b) Which are the two types of natural resources? (c) What are the uses of soil? (d) What is ‘nulla bunding’? (e) What is ‘biotechnology’? (f) What are the differences between renewable and non-renewable resources?

1223.

Write answers to the following questions. (a) What is meant by natural resources? (b) Which are the two types of natural resources? (c) What are the uses of soil? (d) What is ‘nulla bunding’? (e) What is ‘biotechnology’? (f) What are the differences between renewable and non-renewable resources?

Answer»

Write answers to the following questions.

(a) What is meant by natural resources?

(b) Which are the two types of natural resources?

(c) What are the uses of soil?

(d) What is ‘nulla bunding’?

(e) What is ‘biotechnology’?

(f) What are the differences between renewable and non-renewable resources?

Discussion

1224.	Specific resistance of aluminum is 2.63*10 ohm cm. What is meant by this statement
Answer» Specific resistance of aluminum is 2.63*10 ohm cm. What is meant by this statement

Discussion

1225.	State the precautions while using clinical thermometer.
Answer» State the precautions while using clinical thermometer.

Discussion

1226.	Which cell is also called storage cell and can be reused?
Answer» Which cell is also called storage cell and can be reused?

Discussion

1227.	How to make a complete circuit with the switch?
Answer» How to make a complete circuit with the switch?

Discussion

1228.	Explain the following observation very briefly.(a) A firki does not rotate in a closed area.(b) The arrow of weather cock points towards a particular direction at a particular moment.(c) An empty glass in fact is not empty.(d) Breathing through mouth may harm you.
Answer» Explain the following observation very briefly. (a) A firki does not rotate in a closed area. (b) The arrow of weather cock points towards a particular direction at a particular moment. (c) An empty glass in fact is not empty. (d) Breathing through mouth may harm you.

Discussion

1229.	(a) What is an electromagnet? Draw a labelled diagram to show the making of a simple electromagnet.(b) State three factors on which the strength of an electromagnet depends. How does the strength of electromagnet depend on these factors?
Answer» (a) What is an electromagnet? Draw a labelled diagram to show the making of a simple electromagnet. (b) State three factors on which the strength of an electromagnet depends. How does the strength of electromagnet depend on these factors?

Discussion

1230.	The center of a cyclone is a calm area and is called the _________of the storm.
Answer» The center of a cyclone is a calm area and is called the _________of the storm.

Discussion

1231.	Identify the part which acts as fuse in the given circuit:
Answer» Identify the part which acts as fuse in the given circuit:

Discussion

1232.	Question 8Who am I?(a) I’m found in a thermometer, I measure your temperature.(b) I make things hot or cold.(c) I have no shape whatsoever(d) I dissolve in water, but not in kerosene.
Answer» Question 8 Who am I? (a) I’m found in a thermometer, I measure your temperature. (b) I make things hot or cold. (c) I have no shape whatsoever (d) I dissolve in water, but not in kerosene.

1232.

Question 8Who am I?(a) I’m found in a thermometer, I measure your temperature.(b) I make things hot or cold.(c) I have no shape whatsoever(d) I dissolve in water, but not in kerosene.

Answer»

Question 8

Who am I?

(a) I’m found in a thermometer, I measure your temperature.

(b) I make things hot or cold.

(c) I have no shape whatsoever

(d) I dissolve in water, but not in kerosene.

Discussion

1233.	A uniform ladder of length 3.25 metre and weighing 250 newton is placed against the smooth vertical wall with its lower end 1.25 m from the wall if coefficient of friction between the ladder and the floor is 0.3 then find the frictional force acting on the ladder at the point of contact between ladder and floor
Answer» A uniform ladder of length 3.25 metre and weighing 250 newton is placed against the smooth vertical wall with its lower end 1.25 m from the wall if coefficient of friction between the ladder and the floor is 0.3 then find the frictional force acting on the ladder at the point of contact between ladder and floor

Discussion

1234.	the distance of the Moon from the Earth is 3.8 into 10 to the power 5 km calculate the speed of the Moon revolving around the earth mass of the earth = 6.1 into 10 to the power 24 kg and G= 6.7 into 10 to the power minus 11 Newton metre square per kg square
Answer» the distance of the Moon from the Earth is 3.8 into 10 to the power 5 km calculate the speed of the Moon revolving around the earth mass of the earth = 6.1 into 10 to the power 24 kg and G= 6.7 into 10 to the power minus 11 Newton metre square per kg square

Discussion

1235.	A 160 m long train moving on a straight level track passes a pole in 10 s, find the speed of the train and the time it will take to cross an 840 m long bridge.
Answer» A 160 m long train moving on a straight level track passes a pole in 10 s, find the speed of the train and the time it will take to cross an 840 m long bridge.

Discussion

1236.	52. A particle moves from a point -2i+5j to 4j+3k when a force of 4i+3j N is applied. How much work is done by the force?
Answer» 52. A particle moves from a point -2i+5j to 4j+3k when a force of 4i+3j N is applied. How much work is done by the force?

Discussion

1237.	Question 29It is much easier to burst an inflated balloon with a needle than by a finger. Explain.
Answer» Question 29 It is much easier to burst an inflated balloon with a needle than by a finger. Explain.

Discussion

1238.	The distance of the image from a mirror is ______ the distance of the object from the mirror.
Answer» The distance of the image from a mirror is ______ the distance of the object from the mirror.

Discussion

1239.	Question 15 Two mirrors meet at right angles. A ray of light is incident on one at an angle of 30∘ as shown in Fig. 16.19. Draw the reflected ray from the second mirror.
Answer» Question 15 Two mirrors meet at right angles. A ray of light is incident on one at an angle of $30^{\circ}$ as shown in Fig. 16.19. Draw the reflected ray from the second mirror.

Discussion

1240.	Using a pinhole camera, a student observes the image of two of his friends standing in sunlight, wearing yellow and red shirt respectively. What will be the colours of the shirts in the image?
Answer» Using a pinhole camera, a student observes the image of two of his friends standing in sunlight, wearing yellow and red shirt respectively. What will be the colours of the shirts in the image?

Discussion

1241.	Define galaxy.
Answer» Define galaxy.

Discussion

1242.	two cars of the same mass are moving with velocities v1 and v2 respectively if they are stopped by supplying the same braking power in time t1 and t2 respectively then v1v2 is1) t1t2 2) t12t22 3) mt1t2 4) √t1t2
Answer» two cars of the same mass are moving with velocities $v_{1}$ and $v_{2}$ respectively if they are stopped by supplying the same braking power in time $t_{1}$ and $t_{2}$ respectively then $\frac{v_{1}}{v_{2}}$ is 1) $\frac{t_{1}}{t_{2}}$ 2) $\frac{{t_{1}}^{2}}{{t_{2}}^{2}}$ 3) $m \frac{t_{1}}{t_{2}}$ 4) $\sqrt{\frac{t_{1}}{t_{2}}}$

1242.

two cars of the same mass are moving with velocities v1 and v2 respectively if they are stopped by supplying the same braking power in time t1 and t2 respectively then v1v2 is1) t1t2 2) t12t22 3) mt1t2 4) √t1t2

Answer»

two cars of the same mass are moving with velocities $v_{1}$ and $v_{2}$ respectively if they are stopped by supplying the same braking power in time $t_{1}$ and $t_{2}$ respectively then $\frac{v_{1}}{v_{2}}$ is

1) $\frac{t_{1}}{t_{2}}$

2) $\frac{{t_{1}}^{2}}{{t_{2}}^{2}}$

3) $m \frac{t_{1}}{t_{2}}$

4) $\sqrt{\frac{t_{1}}{t_{2}}}$

Discussion

1243.	Total charge on 75kg of electrons
Answer» Total charge on 75kg of electrons

Discussion

1244.	A Rolling ball has which of the following type(s) of motion :
Answer» A Rolling ball has which of the following type(s) of motion :

Discussion

1245.	Question 5 (c)In the following situations identify the agent exerting the force and the object on which it acts. State the effect of the force in each case.(c) A load suspended from a spring while its other end is on a hook fixed to a wall.
Answer» Question 5 (c) In the following situations identify the agent exerting the force and the object on which it acts. State the effect of the force in each case. (c) A load suspended from a spring while its other end is on a hook fixed to a wall.

Discussion

1246.	The radius of the circle A is 15 times the radius of the circle B. Circle A rolls around the circle B and comes back to the point where it started. Then the number of revolutions of the circle A around the circle B is
Answer» The radius of the circle $A$ is $\frac{1}{5}$ times the radius of the circle $B$ . Circle $A$ rolls around the circle $B$ and comes back to the point where it started. Then the number of revolutions of the circle $A$ around the circle $B$ is

Discussion

1247.	What is a periodic motion? Give examples.
Answer» What is a periodic motion? Give examples.

Discussion

1248.	104. The minimum required size of plane mirror to visualise comolete image of an object is
Answer» 104. The minimum required size of plane mirror to visualise comolete image of an object is

Discussion

1249.	Does diffused reflection violate the laws of reflection of light? If not then why?
Answer» Does diffused reflection violate the laws of reflection of light? If not then why?

Discussion

1250.	Look at the pictures and tell the story in your own words.THE UMBRELLA AND THE CROWDisclaimer: Kindly refer the textbook for the images.Rearrange the following sentences in the right order to make it into a story on the left page.• A wind blows.• It is raining.• The crow flies away with the umbrella.• The girl has an umbrella.• The umbrella is now a nest.• The umbrella hangs from a tree.Now say the story in English using the words rain, wind, crow, nest, is, has, blows, flies.
Answer» Look at the pictures and tell the story in your own words. THE UMBRELLA AND THE CROW Disclaimer: Kindly refer the textbook for the images. Rearrange the following sentences in the right order to make it into a story on the left page. • A wind blows. • It is raining. • The crow flies away with the umbrella. • The girl has an umbrella. • The umbrella is now a nest. • The umbrella hangs from a tree. Now say the story in English using the words rain, wind, crow, nest, is, has, blows, flies.

1250.

Look at the pictures and tell the story in your own words.THE UMBRELLA AND THE CROWDisclaimer: Kindly refer the textbook for the images.Rearrange the following sentences in the right order to make it into a story on the left page.• A wind blows.• It is raining.• The crow flies away with the umbrella.• The girl has an umbrella.• The umbrella is now a nest.• The umbrella hangs from a tree.Now say the story in English using the words rain, wind, crow, nest, is, has, blows, flies.

Answer»

Look at the pictures and tell the story in your own words.

THE UMBRELLA AND THE CROW

Disclaimer: Kindly refer the textbook for the images.

Rearrange the following sentences in the right order to make it into a story on the left page.

• A wind blows.

• It is raining.

• The crow flies away with the umbrella.

• The girl has an umbrella.

• The umbrella is now a nest.

• The umbrella hangs from a tree.

Now say the story in English using the words rain, wind, crow, nest, is, has, blows, flies.

Discussion

Explore topic-wise InterviewSolutions in .

Why do we classify the liquids as good conductors and poor conductors instead of conductors and insulators? Explain with an example. [3 MARKS]

Which among the following arrangement is true regarding the speed of light?

the two ends of a metal rod are maintained at temperatures 100C and 110 C .The rate of the heat flowin the rod is found to be 4 J/s.If the ends are maintained at temperatures 200 C and 210 C,the rate of heat flow is?

In optical fibre, refractive index of inner part is 1.68and refractive index of outer part is 1.44. Thenumerical aperture of the fibre is(1) 0.5653(2) 0.6653(3) 0.7653(4) 0.86

(3) 7425 L atm(4O28. An ideal gas is allowed to expand from 5 L to 15 L once rapidly and once very slowly. The magnitude of wor(a)done in two processes are W, and W, they are related as2'(1) W, = W2(2) W, > W2C(3) W< W(4) Data is insufficient

39. if the three vectors a, b, c are non-coplanar. express a, b, c each in terms of the vectors bc, ca, ab.

21. The difference apparent frequency of a source of sound as perceived by an observer during its approach and recession is 2% of the natural frequency of the source. The velocity of the source is [Take speed of sound in air = 300 m/s] (1) 6 m/s (2) 3 m/s (3) 1.5 m/s (4) 12 m/s

Rajiv connected two exactly similar heating elements (or resistances) across a mains supply in two different ways to heat some water.(a) Is more heat obtained when the heating elements are connected in series or when they are connected in parallel?​(b) Give reasons for your answer.

Sound and light waves:

What is the difference between thermal energy and heat energy?

A heavy brass sphere is hung from a weightless inelastic string and used as simple pendulum. its time period of oscillation is T. When this sphere is immersed in a non-vicious liquid of density 1/10 that of brass. If it acts as simple pendulum then find its period

A particle moving in a straight line covers first half of the distance into two equal time intervals with speed of 2 m/s and 4 m/s respectively, and second half with speed of 5m/s. The average speed of the particle is

the strain energy stored in a body of volume v due to shear strain

Question 11How many times is a ray of light reflected by two plane mirrors placed parallel and facing each other?

Given that equilibrium constant for the reaction 2so2+o2__2so3 Has a value of 278k at a particular temperature what is the equilibrium. Constant for the following reaction at the same temparaure So3____so2+12o2

Why does the C.N of solid decrease with the increase in temperature ?

Using the "conduction tester" on an object it is found that the bulb begins to glow. Is that object a conductor or an insulator? Explain.

ntA battery of emf 100V and a resistor of resistance 10 kilo-ohm are joined in series. This system is used as a source to supply current to an external resistance R. If R is not greater than 100 ohm, the current through it is constant up to two significant digits. Find its value.n ntn ntHc 199n

Define potential energy.

calculate the resis†an ce if 5 ampere of electric current flows through a conductor having potential difference between two points is equal to 15 v

An object moved from A to B, covering a distance of 300 m at a speed of 20m/s. It then travelled from B to C, covering another 300 m in 15 seconds. Find the average speed of the object in travelling from A to C, if it stopped at B for 30 seconds.

Specific resistance of aluminum is 2.63*10 ohm cm. What is meant by this statement

State the precautions while using clinical thermometer.

Which cell is also called storage cell and can be reused?

How to make a complete circuit with the switch?

Explain the following observation very briefly.(a) A firki does not rotate in a closed area.​(b) The arrow of weather cock points towards a particular direction at a particular moment.(c) An empty glass in fact is not empty.(d) Breathing through mouth may harm you.

(a) What is an electromagnet? Draw a labelled diagram to show the making of a simple electromagnet.​(b) State three factors on which the strength of an electromagnet depends. How does the strength of electromagnet depend on these factors?

The center of a cyclone is a calm area and is called the _________of the storm.

Identify the part which acts as fuse in the given circuit:

Question 8Who am I?(a) I’m found in a thermometer, I measure your temperature.(b) I make things hot or cold.(c) I have no shape whatsoever(d) I dissolve in water, but not in kerosene.

the distance of the Moon from the Earth is 3.8 into 10 to the power 5 km calculate the speed of the Moon revolving around the earth mass of the earth = 6.1 into 10 to the power 24 kg and G= 6.7 into 10 to the power minus 11 Newton metre square per kg square

A 160 m long train moving on a straight level track passes a pole in 10 s, find the speed of the train and the time it will take to cross an 840 m long bridge.

52. A particle moves from a point -2i+5j to 4j+3k when a force of 4i+3j N is applied. How much work is done by the force?

Question 29It is much easier to burst an inflated balloon with a needle than by a finger. Explain.

The distance of the image from a mirror is ______ the distance of the object from the mirror.

Question 15 Two mirrors meet at right angles. A ray of light is incident on one at an angle of 30∘ as shown in Fig. 16.19. Draw the reflected ray from the second mirror.

Using a pinhole camera, a student observes the image of two of his friends standing in sunlight, wearing yellow and red shirt respectively. What will be the colours of the shirts in the image?

Define galaxy.

two cars of the same mass are moving with velocities v1 and v2 respectively if they are stopped by supplying the same braking power in time t1 and t2 respectively then v1v2 is1) t1t2 2) t12t22 3) mt1t2 4) √t1t2

Total charge on 75kg of electrons

A Rolling ball has which of the following type(s) of motion :

Question 5 (c)In the following situations identify the agent exerting the force and the object on which it acts. State the effect of the force in each case.(c) A load suspended from a spring while its other end is on a hook fixed to a wall.

The radius of the circle A is 15 times the radius of the circle B. Circle A rolls around the circle B and comes back to the point where it started. Then the number of revolutions of the circle A around the circle B is

What is a periodic motion? Give examples.

104. The minimum required size of plane mirror to visualise comolete image of an object is

Does diffused reflection violate the laws of reflection of light? If not then why?

Rajiv connected two exactly similar heating elements (or resistances) across a mains supply in two different ways to heat some water.(a) Is more heat obtained when the heating elements are connected in series or when they are connected in parallel?(b) Give reasons for your answer.

Given that equilibrium constant for the reaction 2so2+o22so3 Has a value of 278k at a particular temperature what is the equilibrium. Constant for the following reaction at the same temparaure So3__so2+12o2

Explain the following observation very briefly.(a) A firki does not rotate in a closed area.(b) The arrow of weather cock points towards a particular direction at a particular moment.(c) An empty glass in fact is not empty.(d) Breathing through mouth may harm you.

(a) What is an electromagnet? Draw a labelled diagram to show the making of a simple electromagnet.(b) State three factors on which the strength of an electromagnet depends. How does the strength of electromagnet depend on these factors?