P2.3 Currents in electrical circuits

Question 1

1. Describe how an insulator becomes charged?

Answer 1

1. Rubbing / friction transfers electrons

Question 2

2. What would happen if two positively charged objects were brought next to each other?

Answer 2

2. repel

Question 3

3. Describe (in terms of electrons and charges) what happens when a charged balloon is brought close to a wall.

Answer 3

3. Balloon is negatively charged, it repels the electrons in the wall, it is attracted to the positive charge left in the wall.

Question 4

4. Define an ‘electric current’ and state what this is in metals.

Answer 4

4. The flow of charge, the flow of electrons

Question 5

5. What type of current do cells and batteries provide?

Answer 5

5. direct current

Question 6

6. How should you put an ammeter into a circuit and what does it measure? Give the units

Answer 6

6. In series, current, Amps

Question 7

7. What is another name for voltage?

Answer 7

7. Potential Difference

Question 8

8. What will happen to the current if the potential difference is increased?

Answer 8

8. Increase

Question 9

9. How should you put a voltmeter into a circuit and what does it measure? Give the units

Answer 9

9. In parallel, voltage or p.d., volts

Question 10

10. Define potential difference

Answer 10

10. 1 Volt is the energy transferred per unit charge/1 joule per coulomb

Question 11

11. Name 3 components shown as an I-V plot?

Answer 11

Filament lamp, Resistor and Diode.

Question 12

12. Explain the effect of increasing resistance on current.

Answer 12

12. Reduces current because it is more difficult for the electrons to flow.

Question 13

13. What p.d. is needed to make a 2A current flow through a 10ohm resistor?

Answer 13

13. 2x10=20V

Question 14

14. What happens to the resistance of a filament amp after it is turned on? How does this affect current?

Answer 14

14. Resistance increases, current decreases.

Question 15

15. What happens to the resistance of a LDR as light intensity increases? What effect does this have on current?

Answer 15

15. Resistance decreases, current increases.

Question 16

16. Explain what happens to a resistor as current passes through it?

Answer 16

16. Heats up because there are collisions between electrons and the ions in the lattice.

Question 17

17. Give a use of the heating effect of a wire

Answer 17

17. Heating element in kettle, fire etc.

Question 18

18. Why is there an increasing use of LEDs for lighting?

Answer 18

18. They use a much smaller current than other forms of lighting.