Physics Quiz

Describe the term 'resistivity' of a material.

• The ability of a material to conduct electricity

• The opposition to the flow of electric current through a material

• The measure of a material's ability to resist electric current per unit length and cross-sectional area

• The amount of charge that flows through a material per unit time

State four factors upon which the resistance value of a conductor will depend.

• Length, cross-sectional area, temperature, and type of material

• Color, texture, flexibility, and length

• Voltage, current, power, and energy

• Weight, strength, elasticity, and thermal conductivity

What is the relationship between magnetic flux, cross-sectional area of flux path, and magnetic flux density?

• The magnetic flux density decreases as the cross-sectional area increases.

• The magnetic flux density is independent of the cross-sectional area.

• The magnetic flux density increases as the cross-sectional area decreases.

• The magnetic flux density is directly proportional to the magnetic flux only.

What is the function of a Residual Current Device (RCD)?

• To prevent electric shocks by interrupting the circuit if there is a difference in current between two conductors.

• To increase the current flow in a circuit.

• To store electrical energy for later use.

• To convert alternating current to direct current.

Which of the following is a benefit of a Residual Current Device (RCD)?

• It provides a stable voltage supply.

• It prevents electric shocks by interrupting the circuit during a fault.

• It increases the efficiency of electrical appliances.

• It reduces the cost of electricity.

What are two advantages of a circuit breaker over a fuse?

• Circuit breakers are more expensive and harder to replace than fuses.

• Circuit breakers can be reset after tripping and provide more precise protection.

• Fuses provide faster protection and are more reliable than circuit breakers.

• Circuit breakers consume more power and have a longer response time than fuses.

Describe the effect on the current with time, when switch S is closed in a DC circuit containing a resistor (R) and a capacitor (C).

• The current immediately drops to zero.

• The current remains constant over time.

• The current gradually decreases to zero as the capacitor charges.

• The current increases exponentially as the capacitor charges.

Describe an inductor.

• A device that converts electrical energy into mechanical motion.

• A component that stores energy in a magnetic field when electric current flows through it.

• A device that increases the voltage of an alternating current.

• A resistor that limits the flow of electric current.

State two examples of the use of inductive components.

• In transformers and electric motors.

• In batteries and solar panels.

• In capacitors and diodes.

• In resistors and switches.

Describe how an electric current may be generated by dynamic induction.

• By moving a magnet near a coil or wire to induce a current.

• By applying a direct current through a wire.

• By heating a wire to a high temperature.

• By using a chemical reaction in a battery.