Ohms Law

Front 1

What are the voltage across and current through a component linked by?

Back 1

Resistance

Front 2

Whats the formula linking voltage and current?

Back 2

v = i x r

voltage = current x resistance

This is Ohms law

Front 3

A 4 Ohm resistor in a circuit has a voltage across it of 6V. What is current?

Back 3

v = i x r

so

i = v / r = 6/4 = 1.5A

Front 4

What does a resistor do?

Back 4

Opposes the flow of current and reduces it (across whole circuit)

Front 5

How do you measure resistance of a component?

Back 5

The resistance of a component can be found by measuring the current flowing through it, and the potential difference across it. Then use r = v / i

For example, 3 A flows through a 240 V lamp. What is the resistance of the lamp?
Resistance = 240 ÷ 3 = 80 Ω

Front 6

How does the current flowing through a resistor at a constant tempertaure link to voltage?

Back 6

The current flowing through a resistor at a constant temperature is directly proportional to the voltage across it. This is Ohms law: voltage = current x resistance. For a fixed resistance, If you double the voltage you double the current.

This is the graph of current against potential difference for a resistor at constant temperature.

Front 7

So, every appliance draws a different amount of current depending on its resistance. What does this do to power then?

Back 7

Power = VI
so the more current the more power used!!

Front 8

Ohms law is a linear relationship, what does this mean?

Back 8

The more volts you have the more current you'll get. Increase the voltage and get more current!!