What is the best definition for potential difference?

• the potential energy per electron.

• the potential energy per unit of charge.

• the kinetic energy per unit of charge.

• the energy carried by an electron.

A student used some everyday items to investigate static electricity.

Figure 1 shows a flexible plastic strip being rubbed with a cloth.

Complete the sentence (with 1 correct word).

Rubbing the plastic strip with the cloth causes the strip to become negatively charged because ____________________ move from the cloth onto the plastic strip.

Figure 1 shows a flexible plastic strip being rubbed with a cloth.

Rubbing the plastic strip with the cloth causes the strip to become negatively charged.

Complete the sentence with 1 correct term.

The cloth is left with a ____________________ charge.

The student hung the negative plastic strip over a wooden rod.

The ends of the strip moved away from each other.

Figure 2 shows the position of the plastic strip on the wooden rod.

What conclusions should the student make about the forces acting on the two halves of the plastic strip? (select as many as apply)

• The electrostatic forces are uneven depending on mass.

• The forces are even magnitude.

• The forces act in opposite directions.

• The forces act diagonally upwards.

The graph below shows how the current through a filament lamp changes after the lamp is switched on.

The normal current through the filament lamp is 1.5 A.

For how many seconds is the current through the filament lamp greater than 1.5 A?

• 0.01 s

• 0.08 s

• 0.09 s

• 0.14 s

The graph below shows how the current through a filament lamp changes after the lamp is switched on.

Why might the filament inside a lamp melt when the lamp is first switched on?

• The current changes rapidly.

• The current drops away quickly.

• The wire might be brittle.

• The current goes higher than normal value.

A lamp is connected to a 24 V power supply. The current through the lamp is 1.5 A.

Calculate the power of the lamp. (Answer to 2 Sig Fig with unit symbol).

LED lamps are much more efficient than filament lamps.

What does this statement mean?

• LED lamps have a similar power output to filament lamps.

• LED lamps waste a smaller proportion of the input energy than filament lamps.

• LED lamps have a higher power input than filament lamps.

• LED lamps waste a larger proportion of the input energy than filament lamps.

The diagram shows a temperature sensing circuit used to control a heating system in a house.

What quantity does the ammeter measure? (One correct word only needed)

The diagram shows a temperature sensing circuit used to control a heating system in a house.

The current in the circuit is 3.5 mA when the potential difference across the thermistor is 4.2 V

Calculate the resistance of the thermistor in Ohms (Answer to 2 sig fig, no units needed)