# Questiosn Ohm's law – answers

Ohm's law
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Slide 1: Tekstslide
Natuurkunde / ScheikundeMiddelbare school

In deze les zitten 15 slides, met tekstslides.

## Onderdelen in deze les

Ohm's law

#### Slide 1 -Tekstslide

Before you do the questions:
1. You are setup in a group through zoom.
2. One of you shares your screen with the presentation on it.
3. One of you writes down the answers you come to in a word document (if this isn't possible, aks mr. Brands for help)
4. Now you're ready, start the questions

#### Slide 2 -Tekstslide

1) What are the three quantities in Ohm's law?

Current
Potential difference
Resistance

#### Slide 3 -Tekstslide

2) What is current? And its unit?

The amount of coulumb that travel thorugh a circuit per second.
Unit: Ampere (coulomb/second)

#### Slide 4 -Tekstslide

3) What is potential difference? and its unit?

The difference in energy per coulomb at two points in a circuit.
Unit: Volt (Joule/coulomb)

#### Slide 5 -Tekstslide

4) What is resistance? and its unit?

How much the flow of current is resisted.
Unit: Ω (Ohm)

#### Slide 6 -Tekstslide

5) What is the relationship between current, potential difference and current?

R=IV

#### Slide 7 -Tekstslide

6) In a circuit a lightbulb gets changed for another lightbulb with a larger resistance. The potential difference over the circuit stays the same. What happens to the current in the circuit? Explain it in your own words and using ohm’s law.

The current becomes weaker because the flow of coulombs gets resisted more.
Ohm's law:                   R becomes bigger, V stays the same. So I must become smaller
I=RV

#### Slide 8 -Tekstslide

7) In a circuit a resistor gets replaced. With the new resistor the current has increased. What can you say about the resistance of the new resistor compared to the old one. Explain.

The resistance of the new resistor must be smaller, since the current through the circuit increased.

#### Slide 9 -Tekstslide

8) What is the correct way of rewriting Ohm's law to use it for calculating current?
I=RV

#### Slide 10 -Tekstslide

9) What is the correct way of rewriting Ohm's law to use it for calculating potential difference?
V=IR

#### Slide 11 -Tekstslide

10) What current flows through the bulb of a 3.00-V flashlight when its resistance is 3.60 Ω?

Given:
V = 3V
R = 3.6 Ω

The current

Formula
I = V/R

Calculation
I = 3/3.6 = 0.83 A

The current is 0.83 A

#### Slide 12 -Tekstslide

11) Calculate the resistance of a pocket calculator that has a 1.35 V battery and through which 0.200 mA flows.
Given:
V = 1.35 V
I = 0.200 A

The resistance

Formula
R = V/I

Calculation
R = 1.35/0.200 = 6.75 Ω

The resistance = 6.75 Ω

#### Slide 13 -Tekstslide

12
a) Find the voltage drop in an extension cord having a 0.0600−Ω resistance and through which 5.00 A is flowing.

b) A cheaper cord utilizes thinner wire and has a resistance of 0.300Ω . What is the voltage drop in it when 5.00 A flows?

a)
Given:
R = 0.06 Ω
I = 5A

The voltage drop (potential difference)

Formula
V = I*R

Calculation
V = 0.06 * 5 = 0.3 V

The voltage drop = 0.3 V

#### Slide 14 -Tekstslide

12
a) Find the voltage drop in an extension cord having a 0.0600−Ω resistance and through which 5.00 A is flowing.

b) A cheaper cord utilizes thinner wire and has a resistance of 0.300Ω . What is the voltage drop in it when 5.00 A flows?

b)
Given:
R = 0.3 Ω
I = 5A