National 5PhysicsSQAExam QuestionsElectricityElectrical Charge Carriers

Electrical Charge Carriers (SQA National 5 Physics): Exam Questions

Exam code: X857 75

15 mins7 questions
11 mark

Alternating current (a.c.) can be defined as a current where

  • only negative charges move

  • charges move in one direction only

  • charges reverse direction at regular intervals

  • only positive charges move

  • the rate of flow of charge is constant

Choose your answer

2
Sme Calculator4 marks
Diagram showing a radioactive source held by tongs above a metal grid, connected to a microammeter and a high voltage power supply.

A radioactive source is placed at a fixed height above the metal grid.

Radiation from the source ionises the air between the metal wire and the grid.

Sparks are produced between the wire and the grid.

In a time of one minute, 96 sparks are observed and the average reading on the ammeter is 0.12 μA.

Determine the average charge transferred between the wire and the grid during each spark.

How did you do?

3
Sme Calculator1 mark

A hair dryer is connected to a 230 V supply. The current in the hair dryer is 2.0 A.

The electrical charge that passes through the hair dryer in 5 minutes is:

  • 10 C

  • 460 C

  • 600 C

  • 1150 C

  • 2300 C

Choose your answer

4
Sme Calculator1 mark

A hairdryer is connected to a 230 V supply.

The current in the hairdryer is 2·0 A.

The electrical charge that passes through the hairdryer in 5 minutes is

  • 10 C

  • 460 C

  • 600 C

  • 1150 C

  • 69 000 C

Choose your answer

5a1 mark

A wireless charger uses radio waves to charge the battery of a mobile phone.

Diagram showing a mobile phone on a wireless charger stand with a power flex. Labels indicate parts: mobile phone, wireless charger, and flex.

The charger is connected to a direct current (d.c.) supply via a flex.

Explain in terms of electron flow what is meant by direct current.

How did you do?

5b
Sme Calculator3 marks

The current in the flex is 2.5 A.

The charger is in use for 1.5 hours.

Calculate the charge supplied to the charger during this time.

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61 mark

A student makes the following statements about a.c. and d.c. circuits.

I In an a.c. circuit the direction of the current changes regularly.

II In a d.c. circuit negative charges flow in one direction only.

III In an a.c. circuit the size of the current varies with time.

Which of these statements is/are correct?

  • I only

  • II only

  • I and II only

  • I and III only

  • I, II and III

Choose your answer

7
Sme Calculator3 marks

A solar jar is designed to collect energy from the Sun during the day and release this energy as light at night.

When the solar jar is placed in sunlight, photovoltaic cells on the lid are used to charge a rechargeable battery.

Diagram of a glass jar with labelled parts including a lid, photovoltaic cells, rechargeable battery, and LEDs.

At night, the rechargeable battery is used to power four identical LEDs.

When the battery is completely discharged it then takes 6∙0 hours of direct sunlight to fully charge the battery. During this time, there is a constant current of 0·135 A to the battery.

Calculate the total charge supplied to the battery during this time.

How did you do?