EoC Exam, static electricity and elect. Quantities

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A wire has a certain electrical resistance.

The diameter and length of the wire may be changed.

Which pair of changes must cause the resistance of the wire to decrease?

• decreasing the diameter and decreasing the length

• increasing the diameter and decreasing the length

• increasing the diameter and increasing the length

• decreasing the diameter and increasing the length

Four students separately measure the electromotive force (e.m.f.) of the battery, the current in the resistors, and the potential difference (p.d.) across resistor R.

Which student shows values with their correct units?

• Sardor

  e.m.f.= 3 V

  current = 0.3 A

  p.d. = 3 V

• Sam

  e.m.f.= 3 A

  current = 0.3 A

  p.d. = 3 V

• Tom

  e.m.f.= 3 V

  current = 0.3 A

  p.d. = 3 ohm

• Jim

  e.m.f.= 3 V

  current = 0.3 C

  p.d. = 3 V

A polythene rod repels an inflated balloon hanging from a nylon thread.

Why do the rod and balloon repel?

• The rod and the balloon have opposite charges.

• The rod and the balloon have like charges.

• The rod is charged but the balloon is not.

• The balloon is charged but the rod is not.

Four students are each given an identical resistor and asked to find its resistance. They each measure the potential difference across the resistor and the current in it.

The results are shown below. One student makes a mistake.

Who is this student?

• Tom

  p.d. = 1.9 V

  current = 0.20 A

• Jim

  p.d. = 3.1 V

  current = 0.29 A

• Lim

  p.d. = 4.5 V

  current = 0.46 A

• Kim

  p.d. = 4.9 V

  current = 0.94 A

In a complete circuit, the conventional current flows through the wire from

• positive to negative battery terminals

• negative to positive battery terminals

If 40 C of charge pass a point in a circuit in 2.0 s, what current is flowing?

• 20 A

• 16 A

• 26 A

• 6 A

If 5 C of charge pass a point in a circuit in 10 s, what current is flowing?

• 0.5 A

• 50 A

• 5 A

• 0.02 A

The circuit shown contains a battery, a 6.0 Ω resistor, and two meters X and Y. One meter records current and one meter records potential difference.

• Meter X: 1.0 A ; Meter Y: 6.0 V

• Meter X: 1.0 V ; Meter Y: 6.0 A

• Meter X: 12.0 A ; Meter Y: 2.0 V

• Meter X: 12.0 V ; Meter Y: 2.0 A

• Ohmic resistor X; filament lamp Y

• Ohmic resistor X; filament lamp Z

• Ohmic resistor W; filament lamp Y

• Ohmic resistor Y; filament lamp X