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# S3 Physics -

Magnetism and Electricity (III) (Calculations). S3 Physics -. 1. 2. 3. 4. 5. 6. 7. 10. 11. 12. 13. 14. 8. 9. 15. 16. 17. answer. What is the current flowing in a circuit if 30C are passed in 1 minute?. Q = It 30 = I x 60 I = 30/60 0.5A. answer.

## S3 Physics -

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1. Magnetism and Electricity (III) (Calculations) S3 Physics - 1 2 3 4 5 6 7 10 11 12 13 14 8 9 15 16 17

2. answer • What is the current flowing in a circuit if 30C are passed in 1 minute? Q = It 30 = I x 60 I = 30/60 0.5A

3. answer 2. What voltage would be measured over a 100 Ω resistor when 10mA flows through it? V = IR V = 0.01 x 100 1V

4. answer 3. How many joules of energy are transferred by a 60W bulb every second? P = E/t 60 = E/1 E =60/1 60J

5. answer 4. Calculate the size of the current flowing in a 3kW mains operated appliance. 13A

6. answer 5. A television draws 0.1 A and has a resistance of 5000Ω. Calculate the power consumption P = IV P = 0.1 x 5000 50W

7. answer 6. How many 1.5V bulbs operating at their correct voltage could be connected in series with a 6V cell? Vs = V1+ V2… 6 = 1.5 +1.5 + 1.5 +1.5 6 = 4(1.5) Four bulbs

8. answer 7. What is the total resistance of a set of Christmas lights comprising of 30 individual 10Ω lamps in series? Rt = R1+R2+… Rt= 30(10) 3600 Ω or 3.6kΩ

9. answer 8. An electrical supply for a caravan delivers a total current of 2A to the fridge and lighting circuits. If the lights use 0.25A, what is the operating current of the fridge? It = Ilights+Ifridge 2= 0.25 + Ifridge I fridge = 2 - 0.25 1.75A

10. answer 9.What is the total resistance of three 90Ω resistors connected in parallel? 1/Rt = 1/R1+1/R2+1/R3 1/Rt = 1/90+1/90+1/90 1/Rt = 3/90 Rt = 90/3 30 Ω

11. answer Work out the enegy used in kWhr for a 2000 W electric heater which is used for 45 mins? E = Pt E= 2(kW)x 0.75(hr) 1.5kWhr

12. answer 11. How many joules are used if a tumble dryer uses 0.75 kWh? 750Whr 750J/s(hr) 750x3600 2700kJ or 2700000J

13. answer 12. Select the appropriate formula from your data book.. That shows the relationship between charge, current and time. Q=It

14. answer 13. Select the appropriate formula from your data book.. That shows the relationship between voltage, current and resistance. V = IR

15. answer 14. State Ohm’s Law. V = IR

16. answer Select the appropriate formula from your data book.. To calculate resistances in series. 15. Rt = R1+R2+R3

17. answer Select the appropriate formula from your data book.. For combining resistors in parallel. 16. 1/Rt= 1/R1 +1/R2 + 1/R3

18. answer 17. State the relationship between Energy and Power P = E/t

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