A copper wire has a resistance of R at room temperature. If the temperature of the wire is increased, what will happen to its resistance?

A. Remains the same

B. Decreases

C. Increases

D. Becomes zero

Which of the following materials has the highest resistivity at room temperature?

A. Silver

B. Copper

C. Iron

D. Rubber

According to Ohm's law, if the voltage across a resistor is doubled, the current through it will:

A. Remain the same

B. Be halved

C. Be doubled

D. Be quadrupled

A device consumes 60W of power when connected to a 240V supply. What is the resistance of the device?

A. 960 ohms

B. 480 ohms

C. 240 ohms

D. 120 ohms

Which of the following is NOT a limitation of Ohm's law?

A. It does not apply to non-linear devices.

B. It does not apply at very high frequencies.

C. It does not apply to superconductors.

D. It does not apply to resistors.

a) Define Ohm's law and state its mathematical expression. [2]

b) A resistor has a constant voltage of 12 V applied across it and carries a current of 3 A. Calculate its resistance using Ohm's law. [3]

a) Explain the concept of resistivity and how it differs from resistance. [3]

b) A copper wire has a length of 2 m, a cross-sectional area of 1 x 10^-6 m^2, and a resistance of 0.1 ohms. Calculate its resistivity. [2]

a) Define electric power and state its relation to voltage and current. [2]

b) A device operates on a voltage of 230 V and draws a current of 5 A. Calculate the power consumed by the device. [3]

a) Describe the relationship between current, resistance, and the heat produced in a resistor. [3]

b) A 10-ohm resistor has a current of 2 A flowing through it. Calculate the heat produced in the resistor in 5 seconds. [3]

c) How would the heat produced change if the current is doubled? [2]

a) Define resistivity and state its unit. [2]

b) A material has a resistance of 8 ohms when its length is 2 m and its cross-sectional area is 2 x 10^-6 m^2. Calculate its resistivity. [3]

c) How would the resistance change if the length of the material is halved while keeping the cross-sectional area constant? [2]

The power dissipated in a resistor can be increased by:

A. Increasing the resistance and keeping the current constant.

B. Decreasing the resistance and increasing the current.

C. Increasing both the resistance and the current.

D. Decreasing both the resistance and the current.

A material has a high conductivity. This means that the material:

A. Has a high resistance.

B. Does not allow the electric current to pass through.

C. Has a low resistivity.

D. Is a perfect insulator.

The temperature coefficient of resistance for a material is positive. This means that:

A. The resistance decreases with an increase in temperature.

B. The resistance remains unchanged with temperature.

C. The resistance increases with an increase in temperature.

D. The material is a superconductor.

Which of the following formulas represents the relationship between power, current, and voltage in a circuit?

A. P = IV

B. P = I^2R

C. P = V^2/R

D. All of the above

A wire has a resistance of 10 ohms at 20°C. If its temperature coefficient of resistance is 0.004/°C, what will be its resistance at 40°C?

A. 10.8 ohms

B. 11.6 ohms

C. 12.4 ohms

D. 13.2 ohms

a) Explain the concept of electric potential energy in an electric field. [3]

b) A charge of 5 x 10^-6 C is placed in an electric field with a potential difference of 200 V. Calculate its potential energy. [3]

c) If the charge is moved to a region with double the potential difference, how would its potential energy change? [2]

a) What are equipotential surfaces? [3]

b) Explain why no work is done by the electric field when moving a charge along an equipotential surface. [3]

c) In a uniform electric field, describe the shape and orientation of equipotential surfaces. [2]

a) State Ohm's law and mention its limitations. [3]

b) A wire of length 4 m and cross-sectional area 1 x 10^-6 m^2 has a resistance of 16 ohms. Calculate its resistivity. [3]

c) If the temperature of the wire is increased, how would its resistance change? [2]

d) Given that the power consumed by the wire is 64 W when a voltage of 8 V is applied across it, determine the current flowing through it. [2]

a) Describe the factors affecting the resistivity of a material. [3]

b) A coil has a resistance of 10 ohms at 20°C. If its temperature coefficient of resistance is 0.004/°C, calculate its resistance at 50°C. [3]

c) Define electric power and state its unit. [2]

d) A device operates at 220 V and draws a current of 5 A. Calculate the power consumed by the device. [2]

a) Explain the concept of electric potential energy in terms of work done. [3]

b) A charge of 2 x 10^-6 C is moved between two points in an electric field with a potential difference of 100 V. Calculate the work done. [3]

c) How does the electric potential energy of a system of two charges change if the distance between them is halved? [2]

d) A battery of 12 V is connected to a resistor of 4 ohms. Calculate the energy consumed by the resistor in 10 seconds. [2]