Question

312 C of charge passes through an electrical device in 143 seconds. If the potential difference across the device is 2.88 volts, determine the energy transfer to the device. 

Answer 1

Explanations & Calculations

• Charge and the time it flows give the current.
• Once the current is found, the energy transferred to the device can be found by the product: $\small V\times I$ .
• That gives the answer.
• Units should be in "Coulombs", "seconds" which give the current in "Amperes". "Amperes" and "volts" give the power in "Joules".

$\qquad\qquad \begin{aligned} \small I&=\small \frac{Q}{t}\\ \\ \text{Power}&=\small VI\\ &=\small V.\frac{Q}{t}\\ &=\small (2.88\,V).\Big(\frac{312\,C}{143\,s}\Big) \end{aligned}$

• You now can get the answer upon simplification.