# 18.1

From TuHSPhysicsWiki

## Contents

- 1 1. How much current flows if you connect a 2.34 ohm resistor to a 12.0V battery?
- 2 2. If 0.129 amps of current flow through a 45 ohm resistor, what is the power dissipated?
- 3 3. If a current of 345mA flows, how much charge will pass by in one minute?
- 4 4. A 85 ohm heating element is connected to 120V. In what time can the heating element raise the temperature of 2.4kg of water initially at 12C to 85C?
- 5 5. A 1200W heater runs on alternating current with a peak voltage of 134V. What is its resistance?

### 1. How much current flows if you connect a 2.34 ohm resistor to a 12.0V battery?

Use I = V/R

I = 12/2.34

I = 5.128A

### 2. If 0.129 amps of current flow through a 45 ohm resistor, what is the power dissipated?

Use P = (I^2)(R)

P = (.129^2)(45)

P = .7488W

### 3. If a current of 345mA flows, how much charge will pass by in one minute?

Use I = Q/T

Q = (.345)(60)

Q = 20.7C

### 4. A 85 ohm heating element is connected to 120V. In what time can the heating element raise the temperature of 2.4kg of water initially at 12C to 85C?

Use (V^2)/R = ((m)(c)(delta Temp))/time

120^2/85 = (2.4*4186*(85-12))/t

t = 4329.02, about 4300sec

### 5. A 1200W heater runs on alternating current with a peak voltage of 134V. What is its resistance?

Vrms=134/(square root of 2)

Vrms=94.7

P=(V^2)(R)

R = (94.7^2)/1200

R = 7.48 about 7.5ohms