A fax machine uses 0.106 A of current in its normal mode of operation, but only 0.040 A in standby mode. The machine uses a potential difference of 120 V. (a) In one minute, how much more charge passes through the machine in normal mode versus the standby mode, and (b) how much more energy is used?

Explanation:

Given that,

Fax machine uses a current of 0.106A on normal mode

I = 0.106A

The fax machine uses a current of 0.04A on stand by mode

I' = 0.04A

The potential different is 240V

V = 120V

A. In one minute, charges that pass through the fax machine between the standby mode and normal mode

t = 1minute = 60seconds

Charge is given

Q = it

So, the charge that pass through the fax machine is

Q = It — I't

Q = (I — i') t

Q = (0.106 — 0.04) × 60

Q = 3.96C

B. Work in electric field is given as

W = QV

Where

W = work

Q = charge

V = potential difference

W = 3.96 × 120

W = 475.2 J