Physics P1

Front 1

What is specific heat capacity?

Back 1

It tells you how much energy stuff can store.

Front 2

It takes 5000J to heat 50g of a substance by 40ºC. Calculate its specific heat capacity.

Back 2

Energy=Mass × Specific Heat Capacity(SHC) × Temperature Change(Temp.Ch.)"
So SHC = Energy ÷ (Mass × Temp.Ch.)"
=5000 ÷ (0.05 × 40)"
= 2500 J/kg/ºC"

Front 3

Explain why heating a pan of boiling water doesn't increase it temperature.

Back 3

You are still putting energy into the substance but it’s used for breaking inter molecular forces rather than raising the temperature which is why you get flat spots on graphs.

Front 4

How much energy is needed to boil a pan dry of 500g of water at 100ºC. (Specific Latent Heat of water for boiling = 2 260 000 J/kg.

Back 4

Energy = Mass × Specific Latent Heat (SLH)"
= 0.5 × 2 260 000"
= 1 130 000 J"

Front 5

Briefly describe how heat is transferred through a) conduction b) convection c) radiation.

Back 5

Conduction of heat is the process where vibrating particles pass on extra kinetic energy to neighbour particles.
Convection occurs when the more energetic particles mover from the hotter region to the cooler region -- and take their heat energy with them.
Radiation- heat is radiated as infrared waves – these are electromagnetic waves that travel in straight lines at the speed of light. Radiation is different to convection and conduction in many ways one being because it can ONLY occur through transparent substances, like air, glass and water.

Front 6

Describe how heat is transferred through a) under a grill and b) in a microwave oven

Back 6

A grill heats food by infrared (heat) radiation. The heat is radiated by a grill is absorbed by the surface of particles of the food, increasing their kinetic energy. The heat energy is then either conducted or convected to more central parts.
Microwave ovens use radiation to cook food too. – Microwaves are electromagnetic waves that have a different wavelength of infrared. Microwaves penetrate about 1cm into the outer layer of food where they are absorbed by water or fat molecules, increasing their kinetic energy. The energy is then conducted or convected to other parts.

Front 7

Describe 4 ways of saving energy in the home and how each one works.

Back 7

1) Loft insulation -- fiberglass wool is laid across the loft space and reduces conduction through the ceiling and into the loft space.
2) Cavity walls and Insulation—two layers of bricks with a gap between them to reduce conduction but you still get some energy lost by convection. Squirting insulation foam into the gap traps pockets of air to minimise this convection. (heat is still lost through the walls by radiation though. Also, if there are any spaces where air is not trapped there’ll still be some convection too).
3) Double glazing – two layers of glass with and air gap between reduce conduction.
4) Draught proofing – strips of foam and plastic around the doors and windows stop hot air from getting out – reducing convection.

Front 8

How much energy is wasted is a hairdryer is 20% efficient has a total energy input of 200 000J?

Back 8

Energy = Useful energy output ÷ Total energy input"
so Useful = Efficiency × Total energy "
=0.2 ×200 000"
=40 000"

Front 9

Sketch a Sankey Diagram to show the energy transformations in the hairdryer mentioned above.

Back 9

.

Front 10

Explain the main features of a transverse wave.

Back 10

Amplitude – The displacement from the rest position to the crest. (NOT from the trough to the crest).
Wavelength (λ)– The length of the full cycle from crest to crest.
Frequency – The number of complete cycles or oscillations passing a certain point per second. Frequency is measured in hertz (Hz). 1 Hz is 1 wave per second.

Front 11

What is the angle of Incidence equal to?

Back 11

The angle of Reflection

Front 12

What are the main features of a plane mirror.

Back 12

Incident light ray
Shiny side of mirror
Reflected light ray
Dull side of mirror

Front 13

List the 7 types of electromagnetic waves in order of wavelength (smallest to largest).

Back 13

Radio Waves, Micro Waves, Infrared, Visible Light, Ultra Violet, X-rays, and Gamma Rays.

Front 14

Explain why morse code is a digital signal.

Back 14

Morse code is a digital signal because the light pulse is only either on or off.

Front 15

Describe how light signals can travel through optical fibres.

Back 15

The waves bounce off the sides off of a very narrow core which is protected by outer layers.

Front 16

Explain the properties of laser beams that make them a) monochromic and b) coherant.

Back 16

a) when all the waves in the laser beam are the same wavelength and frequency.
b) when all the waves have a fixed phase difference i.e. the waves are 'In Phase'.

Front 17

Describe how lasers are used for CD players.

Back 17

A laser shone onto the CD is reflected from the shiny bottom surface as it spins around the player. The beam is then reflected from a land and pit slightly differently -- and this difference can be picked up by a light sensor. these signals are reflected signals that can be changed into an electrical signal. The change in the reflected beam represents on and no change represents off.

Front 18

Briefly describe how infrared radiation is used to control electrical equipment.

Back 18

because the waves aren't visible the pulses act as a digital on/off code. The device will then detect and decode the pattern of pulses coming from the remote control and follow the coded instruction. E.g. a CD player is programmed to know a certain sequence of pulses to play a CD. But each CD has a different sequence of pulses.

Front 19

Explain why long-wave radio waves can bend around obstacles.

Back 19

Longer wavelengths can encounter a lot of diffraction because they are large compared with the gap of obstacles. This means that they are able to bend around tall buildings, hills and any other obstacles.

Front 20

Briefly describe what happens to radio waves in the ionosphere.

Back 20

Radio waves have very short wavelengths, so short wave radio signals with wavelengths of about 10m-100m can be received at long distances from the transmitter because of reflection in the ionosphere.

Front 21

Give 2 advantages and 2 disadvantages of using DAB (Digital Audio Broadcasting)

Back 21

Advantages- DAB suffers less interference because many other stations can be broadcast at the same frequency (multiplexing), And more radio stations are available because of this.
Disadvantages- You need a DAB radio set to pick up an decode the signals, and the sound quality is often not as good because of the compression of the signal.

Front 22

Describe how satellites are used for communication.

Back 22

For satellite TV and phones the signal from a transmitter is transmitted into space where it is picked up by the satellite's receiver dish orbiting thousands of kilometers above the earth. The satellite transmits the signal back to earth in a different direction where it is received by a satellite dish back on earth.

Front 23

Why are Micro- wave transmitters located in high places and close together?

Back 23

They are located high up and close together because they need to pass through the earths watery atmosphere

Front 24

Explain why scientists are concerned about the dangers of a) mobile phone use, and b) the thinning of the ozone layer.

Back 24

a) scientists are concerned about the use of mobile phones because certain tests and experiments have shown there that could be a link between mobile phone use and brain cancer.
b) Scientists are concerned about the thinning of the ozone layer because Some of the problems include the global warming, rise in sea level, and melting of glaciers which are something scientists would like to avoid as much as possible. The ozone depletion also means the presence of the UV radiations on the surface causing serious problems like skin cancer, eye cataract, suppression of immune system etc.

Front 25

Explain how diffraction affects the size of the receiver needed to pick up different wave signals.

Back 25

.

Front 26

Explain the difference between analogue and digital signals.

Back 26

Analogue signals take any value where as digital is just on or off (0 or 1).

Front 27

Why are CFC's so bad?

Back 27

Because they are gases that react with the ozone molecules and break them up making the ozone layer thinner.

Front 28

Name and describe 2 types of wave caused by an earthquake.

Back 28

P-Waves - they travel through solids and liquids and also they are faster than S-Waves. They also pass through the liquid outer core.
S-Waves - They can only travel through solids and are slower than P-Waves. They do not pass through the liquid outer core.