physics m1

Why does friction cause an object to become negatively charged?(static electricity)

Transfer of electrons from one object to another

Why does a negatively charged person experience a shock when they touch something?

There is a potential difference between them
Electrons transfer FROM the charged person
Which earths the charge

Why do conductors decrease the electric shock that someone faces if they are negatively charged?

Material has a low resistance
So there is smaller potential difference between objects

RP3 - how does the resistance vary with length in circuits

Measure the length
Vary the length each time
Measure the current and potential difference each time
Repeat readings
Calculate resistance at each length
Formula
Plot a graph of resistance against length
Hazards: high current may cause skin burns so use low current

Why does switching the circuit off between readings improve accuracy?(RP3)

The temperature of the wire would not change

How does resistance of a component change as potential difference increases across it?

The current increases
Temperature of the filament increases
So the resistance increases

What does more energy efficient mean?

A higher porportion of the total energy is usefully transferred

For an LDR, what happens to the potential difference and current when the light intensity decreases?

Potential difference increases, current decreases

Why is it safe to use a source of alpha radiation in a house?

Alpha radiation does not penetrate skin

Explain the ideal properties of a radioactive source for use in medical diagnosis

short half life or half life or a few hours means less damage to body
Low ionising power also means this
Highly penetrating means it can be detected outside the body

Why does taking repeat readings provide more accurate data?

You can calculate a mean
You can identify and remove anomalies

What type of error would be caused if the student’s eye was not in line with the level of the liquid in the tube during a measurement?

Random error because eye position would not be the same each time relative to the liquid

Explain how a temperature increase would affect the pressure exerted by the gas

It would increase the pressure in a tube even if the volume was constant
Because it would mean higher average kinetic energy of particlesW

What would doing work on an enclosed gas lead to?

Work is done on the air so the temperature of the air increases

What are the advantages of nuclear power?

No carbon dioxide emitted
Doesn’t cause global warming
More energy released per kg of fuel

Describe the process of nuclear fission

a neutron is absorbed by a nucleus
the nucleus splits into two nuclei releasing energy, gamma rays, and neutrons

What does power mean?

Energy transferred per second

Required practical 2

Set up the apparatus by placing a small beaker inside the larger beaker

Fill the small beaker with boiling water from a kettle

Place a piece of cardboard over the beakers as a lid. It should have a hole suitable for a thermometer and place the thermometer through this hole and into the water in the small beaker

Record the temperature of the water in the small beaker and start the stopwatch

Record the temperature of the water every 2 minutes for 20 minutes, or until the water reaches room temperature

Repeat the experiment, each time changing the cardboard for another insulating material (in any order) and also without any insulation at all

Explain why contamination of the inside of the human body by a radioactive material that emits alpha radiation is highly dangerous.

Alpha radiation is highly ionising causing an increased risk of cancer until the radioactive material is removed

What is the frequency of the mains electricity supply in the UK?

50 hz

Why do switches need to be on?

So charge can flow

When moving down, why is increase in kinetic energy is less than decrease in gravitational potential energy.

Work done against air resistance means some thermal energy is transferred to the surroundings

What is the force when a balloon rubs on a person’s hair?

Electrostatic attraction between hair and balloon

How does internal energy of a liquid change as it is heated(no state change)?

Mean kinetic energy of particles increases
Which increases internal energy of substance

How is the particle model used to explain the difference in density between a liquid and a gas?

Particles in a gas have more potential energy than particles in a liquid.