Additional Physics – Forces

L/O :- To know what affects the resistance in a circuit

“Resistance is futile!”

Exam Date -

Quick quiz • What is the equation for work done?• What affects your momentum?• How do you work out speed?• What 2 equations can you use to work out

acceleration?• What is acceleration measured in?• What is the equation for work done and

what is it measured in?• What is Hooke’s law?• What is the equation for working out

current?• Name 3 things which can affect stopping

distance

Can you remember what these symbols mean?

Heater FuseMotor Transformer LED (light emitting diode) Diode Lamp Generator

1

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Resistance

Electrons passing through a bulb have to push their way through lots of vibrating ions in the metal filament. The ions resist the passage of

electrons through the bulb

Resistance = Potential difference (volts) (ohms) Current (amperes)

What is electrical resistance?

What do you think affects the resistance of

a wire?

Write a hypothesis to investigate?

What affects the resistance of a wire?

Hypothesis

Prediction

Independent variable =

Dependent variable =

Method

Equipment

Independent

Voltage (V)

Current (A)

Resistance (Ω)

Gather your results and graph these. You will be expected to tell the class what patterns you found in your results at the end of the lesson

Independent Variable

Do your results support your prediction?

What do the results of the rest of the class tell you about what affects the resistance of a wire?

Do your results follow ohm’s law?

Ohm’s Law

The current through a resistor at constant temperature is directly proportional to the

potential difference across the resistor

If not, why not?

What have you learnt?

•Do you know the equation for resistance?•Can you explain what resistance is?•Do you know what affects resistance?