# Charge, Resistors and Current Questions

1. 45 A of current passes through a cross section of wire. How many charges pass through in 3 seconds?

A. 9.375 x 10^19

B. 3.59 x 10^16

C. 2.16 x 10^17

D. 8.4 x 10^20

2. A 30 ohm resistor dissipates 500W of power. What current is running through the resistor?

A. 15000 A

B. 16.6 A

C. 4.06 A

D. 0.052 A

3. How is current affected if the number of charge carriers decreases?

A. The current increases.

B. The current decreases.

C. The current initially decreases and then is gradually restored.

D. The current is not affected.

4. The current in an electron beam in a cathode-ray tube is 7.0 x 10^-5 A. How much charge hits the screen in 5.0 s?

5. A wire carries a steady current of 0.1 A over a period of 20 s. What total charge moves through the wire in this time interval?

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#### Solution Preview

1.)

Because, I = q/t,

i.e.,

45A current means 45 coulomb charge pass throgh the given cross section in 1 second.

Therefore, the charge which can pass through the given cross-section in 3 seconds = 3*45 = 135 Coulomb

Because, ...

#### Solution Summary

The solution applies simple, easy-to-understand formulae linking charge and current together in order to answer these short multiple choice questions concerning charge carriers and current through resistors.