Electrical Engineering > QUESTIONS & ANSWERS > Electricity Calculations. Questions and Answers. WELL illustrated workings. graded A+. (All)

Electricity Calculations. Questions and Answers. WELL illustrated workings. graded A+.

Document Content and Description Below

Calculate the amount of charge that flows when a current of 3.8 A flows for 9 minutes. Time in seconds = 9 x 60 = 540 s Q = I x t Q = 3.8 x 540 Q = 2100 C Clearly write out your unit conversions... . It means that if you make a mistake, you may still get marks for your working. 2. Calculate the current when 1.9 C of charge flows in 18 seconds. Q = I x t 1.9 = I x 18 I = 1.9 / 18 I = 0.11 A (110 mA) Always write out the equation in full to begin your calculation. 3. Calculate the potential difference across a component with a resistance of 260 Ω when a current of 35 mA flows through it. Current in amps = 35 x 10-3 = 0.035 A V = I x R V = 0.035 x 260 V = 9.1 V Look out for unit prefixes before values in the question. 4. Calculate the resistance of a component when a potential difference of 1.5 V causes a current of 23 mA to flow. Current in amps = 23 x 10-3 = 0.023 A V = I x R 1.5 = 0.023 x R R = 1.5 / 0.023 R = 65 Ω 5. Calculate the power output of an appliance with a potential difference of 240 V and a current of 10.5 A. P = I x V P = 10.5 x 240 P = 2500 W 6. Calculate the current through a 3.1 kW appliance when a potential difference of 200 V is applied. Power in watts = 3.1 x 103 = 3100 W P= I x V 3100 = I x 200 I = 3100 / 200 I = 16 A Always substitute before re-arranging. 7. Calculate the energy transferred when a 4.6 kW appliance is turned on for 30 minutes. Power in watts = 4.6 x 103 = 4600 W Time in seconds = 30 x 60 = 1800 s E = P x t E = 4600 x 1800 E = 8300000 J (8.3 MJ) You can use unit prefixes in your answer if it makes it easier to write down. [Show More]

Last updated: 2 years ago

Preview 1 out of 101 pages

Buy Now

Instant download

We Accept: