Explore topic-wise InterviewSolutions in .

Correct option is D) Luigi Galvani

Correct option is A) Dynamo

Correct option is  C) UK

Correct option is  B) parallel

Following are our daily activities in which we use electricity. 

1. Electric bulb and fluorescent lights etc. 

2. Washing machine and Grinder 

3. Electric fan and Electric iron 

4. Television and Tape recorders 

5. Computers and Motors to lift water etc.

Correct option is  A) Thomas Edison

Electricity requires a closed path for it to flow.

Correct option is  D) Michael Faraday

Correct option is  A) Thales of Miletus

Potentiometer is a device which does not draw any current from the circuit and still measures the potential difference.

Cadmium cell or Leclanche cell.

Potential gradient k = \(\frac{V_{A B}}{l_{A B}}\)
So, the sensitivity of potentiometer can be increased by increasing the length of the wire of potentiometer.

A cell contains some chemical substances which can produce electricity with two terminals.

The number of terminal (s) in an electric cell are two

It only happens when the connection of the circuit is not complete or the wire are not properly connected or the bulb is damaged.

1. Why do you wear gloves? 

2. With what the gloves are made up of? 

3. How do these gloves help in your work? 

4. What will happen if the glows are made up of cloth instead of rubber?

In figure 

(b) the terminals are connected wrong. Bulb will glow when red wire connected to positive terminal of cell and black wire connected to negative terminal of cell.

1. The cell used might have been totally discharged. 

2. The bulb taken might have been fused. 

3. The switch arranged may not be in touch with the wires as expected. 

4. Any breakages in the circuit cause failure.

An electric circuit provides a complete path for electricity to flow between the cell and the bulb.

1. Electricity plays a key role in modern technology. 

2. Without electricity, most of the things could never work. (i.e. TV, Computer, bulb, etc…) 

3. We can’t imagine our life without electricity. 

4. Electricity is a gift given by scientists to human beings.

 5. Electricity is a basis for new inventions.

Correct option is  B) opens

l₂ = ?

R₂ = 13.25Ω

l₁ = 75cm

R₁ = 3.25Ω

l₂/l₁ = R₂/R₁

l₂ = R₂l₁/R₁ = 13.25 x 75/3.25

l₂ = 305.76cm

(a) increase

Ohmic resistances : “Conductors which obey ohm’s law are called ohmic resistances.” 

Two examples : Vanadium, all pure metals like Cu, Al, etc.

As the effective resistance is 6Ω less than 15Ω 

∴ Resistance R must be connected in parallel with 15Ω 

1/15 + 1/R = 1/6 = 1/R = 1/6 – 1/15 = 5—2/30 = 1/10 

∴R = 10Ω

Ohmic Resistors : The resistors which obey Ohm’s law are called the Ohmic resistors or linear resistances. For such resistors, a graph plotted for the potential difference V against current I is a straight line. 

(i) Thin wire will have more resistance. (ii) Specific resistance of both wire is same.

A wire is cut into 3 peices 

Also Resistance of wire is proportional to length Resistance ∝ 1 

Let length of wire =31 = 27Ω 

Resistance of each piece, 1 = 27/3 = 9Ω 

When connected in parallel Resultant resistance of combination 

R is 1/R = 1/9 + 1/9 + 1/9 = 3/9 = 1/3 

∴R= 3Ω

Slop of V-I graph gives us the resistance of the resistor. Slope of A is less, therefore, combination A has less resistance as compared to B. Further, since the net resistance decreases in parallel combination, therefore, A represent the parallel combination. 

Characteristics of parallel circuit: 

1. Pot. difference of each resistance is same. 

2. Current divides [I = I₁ + I₂ + I₃…] 

3. I/R = I/R₁ + I/R₂ + I/R₃ reciprocal of total resistance is the sum of reciprocals of individual resistances. 

4. Total resistance is less than the least of individual resistances. 

Ohm’s Law : “Physical conditions like temp. remaining the same potential across the ends of a conductor is directly proportional to the current flowing”.

(a) internal resistance of cell

Ohms’Law is obeyed only when temperature remains constant.

1. The switch allows the flow of electricity when it is ON and cuts off the flow of electricity when it is OFF. 

2. In this way, the switch is used to allow / stop the flow of electricity to the bulb or any other electrical device. Label the parts in the following figure.

1. Glass chamber 

2. Filament 

3. Metal cap 

4. Terminals

Correct option is  B) 2

1. Yes, the bulb will glow. 

2. Since the connections are perfectly done in the closed circuit.

(i) Two, Positive (+) & Negative (- )

(ii) insulator

(iii) terminals

(iv) terminals cell

(v) glow

(vi) single wire

(vii) carbon

(viii) cotton

1. No, the bulb will not glow. 

2. Here in this arrangement the circuit is not completed. 

3. The handle of the screw is an insulator.

Correct option is  B) Battery

1. conductors

2. filament

Correct option is  D) A plastic clip

Correct option is  C) Positive terminal

Correct option is  B) conductors

A) A switch is the source of electric current in a circuit

In closed circuit the switch remains in ON position and electric current flows in the circuit while in open circuit switch remains in OFF position and current does not flow in the circuit. In closed circuit the appliance works and in open circuit the appliance does not work.

D) 1 – B, 2 – C, 3 – A

(a) Charge and Energy Conservation Laws
Kirchhoffs first law is based on law of conservation of charge and second law is based on law of conservation of energy.

(b) Infinite
Effective resistance of potentiometer is infinite.

(a) R₁ – R₂
I₁ = I ₂ = 1 amp
∴ Potential at a, V_a = I₁ × R₁
= 1 × R₁ = R₁
Potential at b, V_b = I₂R₂ = 1 × R₂ = R₂
V_a – V_b = R₁ – R₂

(d) 0.25 A
From Kirchhoff’s second law
ΣE = IR
2 – 4 = -2I – 5I – I
-2 = -8I
I = \(\frac{2}{8}\frac{1}{4}=\) 0.25 A