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1. We know that switch Is used to open or dose a circuit 

2. When the switch is ‘off’ position, bulb does not glow, because the circuit Is opened. 

3. If we keep the switch in ‘on’ mode, the circuit is closed and the bulb glows.

1. In our daily life we use dry cells in torch lights, wall clocks, radios etc. 

2. Dry cell consists of an electrolyte in dried form. 

3. So, it is easy to move anywhere.

Solution :

The physical quantity coulomb/second called Ampere.

The apparent power is the vector sum of real and reactive power.

Engineers use the following terms to describe energy flow in a system (and assign each of them a different unit to differentiate between them):

• Real power (P) [Unit: W]
• Reactive power (Q) [Unit: VAR]
• Complex power (S)
• Apparent Power (|S|) [Unit: VA]: i.e. the absolute value of complex power S.

P is the real power, Q is the reactive power (in this case negative), S is the complex power and the length of S is the apparent power.

The unit for all forms of power is the watt (symbol: W). However, this unit is generally reserved for the real power component. Apparent power is conventionally expressed in volt-amperes (VA) since it is the simple product of rms voltage and rms current. The unit for reactive power is given the special name "VAR", which stands for volt-amperes reactive (since reactive power flow transfers no net energy to the load, it is sometimes called "wattless" power). Note that it does not make sense to assign a single unit to complex power because it is a complex number and it is therefore defined as a pair of two units: W and VAR.

1. Drawing circuit diagrams with realistic components is difficult.

2. If the circuit is a bigger one with several components it is much more difficult. 

3. To overcome this, standardized symbols of electric components are used to draw the circuit diagrams.

It must have high specific resistance and high melting point.

(i) (a) Use of coal or nuclear fuel to generate electricity and resulting environmental pollution.
(b) Emission of harmful gases by air-conditioners, a refrigerator and its harmful effect on environment.
(ii) (a) Common good/avoidance of wastage of energy.
(b) Environmental care.
(iii) Comparison of monthly bills for electrical energy consumption and creating awareness about minimising the same. Thus saving energy as well as the environmental protection.

When an electric current is passed through a high resistance wire, the wire becomes very hot and produces effect of current. This effect is used in room heaters and electric ovens.

Tungsten is used for making the filaments of an electric bulb.

(a) Potential difference is measured in volts by using a voltmeter placed in parallel across a component. (b) Copper is a good conductor Plastic is an insulator

The correct option is B) 2 is correct.

Given: 

Mass of the object = 2 kg, 

Charge = 10 C, 

Potential difference = 20 V, 

Calculations: 

We know that the Energy transferred which a charge q is moved through a potential difference V is given by 

E = q . V 

Where, 

Q is the charge 

V is the potential difference 

Also gravitational potential energy stored in an object is given as: 

E= m× g× H 

Where,

M is the mass of the object, 

G is gravitational acceleration, 

H is the displacement, 

As per the problem both are equal, 

m.g.x = q. V 

Putting the values in tehequation, we get 

2× 10× x = 10. 20 

x = \(\frac{20}{2}\)

= 10 meters.

Here in this diagram, say: 

R₁ = 4Ω 

R₂ = 8Ω 

R₃ = 4Ω 

R₄ = 8Ω 

When we want to find the resistance across points A and B then resistance R₁ and R₂ are connected in series and resistances R₃ and R₄ are also connected in series.

Thus, 

R₅ = R₁ + R₂ = 4Ω + 8Ω = 12Ω 

And, R₆ = R₃ + R₄ = 4Ω + 8Ω = 12Ω 

Now, this R₅ and R₆ are connected to each other in parallel. Thus the equivalent resistance R_AB across points A and B is:

\(\frac{1}{R_{AB}}=\frac{1}{R_5}+\frac{1}{R_6}\)

\(\frac{1}{R_{AB}}=\frac{1}{12}+\frac{1}{12}\)

\(\frac{1}{R_{AB}}=\frac{2}{12}+\frac{1}{6}\)

∴ R_AB = 6Ω

If wire A has four times the resistance, then it must have the smaller crosssectional area since resistance and cross-sectional area are inversely proportional. In fact, A must have one-fourth the cross-sectional area of B. Since the cross-sectional area of a circular cross-section is given by the expression:

A = π x r²

Wire A must have one-half the radius of wire B and therefore one-half the diameter. Put another way, the diameter of wire B is two times greater than the diameter of wire A.

By connecting resistors in parallel, resistance 1Ω is obtained

Req = R/n = 5Ω/5 = 1Ω.

In a series connection of resistors, the same current passes through all the resistors. Hence, current will be same. Ratio of the current will be 1 : 1.

Correct Answer is: (d) √1.5v

Potential at ∞ = V_∞ = 0.

Potential at the surface of the sphere = V_s = k Q/R.

Potential at the centre of the sphere = V_c = 3/2 k Q/R .

Let m and -q be the mass and the charge of the particle respectively.

Let v₀ = speed of the particle at the centre of the sphere.

1/2 mv² = - q [V_∞ - V_s] = qk Q/R

1/2 mv₀² = - q [V_∞ - Vc] = q. 3/2 k Q/R.

Dividing, v₀²/v² = 3/2 = 1.5 

or v₀ = √(1.5v).

Correct Answer is: (d) None of the above.

Correct Answer is: (a) in all cases

The answer is (b) (ii)

The resistance offered by the electrolyte inside the cell to the flow of current is called internal resistance of cell.

I = nE/(R + nr') cell in series.

We know, R∝ l. In a series combination of resistors, the effective length of the cross-section of the conductor increases, so the resistance increases.

The cord of the electric heater is made of copper. It does not glow because negligible heat is produced in it by the passing current due to its extremely low resistance. The heating element of an electric heater is made of nichrome. It glows because a large amount of heat is produced in it by the passing electric current due to its high resistance.

 The resistance of an ideal ammeter is Zero.

The resistance of an ideal voltmeter is ​Infinite.

Heat produced, H= I² Rt, where 't' stands for time, for which current I is passed through the conductor.

(a) Turn the switch to right side so as the resistance decreases. 

(b) Turn the switch to the left side so as the resistace increases.

The resistance of 60watt bulb is greater than the resistance of 100watt bulb.

The ISI mark ensures the quality of appliances and safety of users.

Bulb : Bulb is a light source which converts electrical energy into light energy.

The devices which act as magnets when electricity passes through them are called electromagnets.

60 watt bulb, because power is inversely proportional to the resistance.

Electrical energy consumed by an electrical appliance depends on: 

1. Power rating of the appliance. 

2. Time for which the appliance is used. 

Power P = w/t = Electrical energy / t

.’. Electrical energy = P × t

The production of heat due to the flow of electricity through a wire is called ’Heating' effect of electricity’.

Electric resistance (R) is defined as the ratio of the voltage applied (V) to the current(I) flowing through the circuit. 

It is given by the formula:

R = \(\frac{V}I\)

Its SI unit is known as ohm (Ω).