Question

1. What is the SI unit of emf?


2.A complete series circuit consists of a 12.0 V battery, a 4.70 Ω resistor, and a switch in the closed position. The internal resistance of the battery is 0.30 Ω. What does an ideal voltmeter read when placed across the resistor?

Answer 1

VOLT

USE OHMS LAW V=IR

GREAT WORK SO FAR KEEP IT UP TIGER

Answer 2

Answer:

1. volt
2. 11.3 V

Explanation:

1. The volt is the derived SI unit for EMF that has been given a special name. It is equivalent to a watt per ampere, where the watt, too, is a derived unit.

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2. Total circuit resistance is 4.7Ω + 0.3Ω = 5.0Ω, so the circuit current is ...

  (12 V)/(5.0 Ω) = 2.4 A

Then the voltage across the resistor is ...

... (2.4 A)×(4.7 Ω) = 11.28 V ≈ 11.3 V

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Comment on Ohm's Law

I've found the attached diagram to be helpful for remembering the relationships involved in Ohms Law. If you cover the letter of the variable you want to find, the other two show you how to find it.

V = I×R

I = V/R

R = V/I