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Question 1

What are the possible dangers of microwaves? (3)

Answer 1

• Can cause MUTATIONS (cancer)/damage cells
• Affect the BRAIN
• Cause INTERNAL HEATING of body tissues

Question 2

What is the hazard associated with infrared radiation?

Answer 2

Is felt as heat (like in heaters, toasters, grills) so can cause skin BURNS

Question 3

What are the reasons for some people thinking that microwaves in mobile phones are not hazardous? (3)

Answer 3

• WEAKER radiation than microwave oven
• LOW intensity
• Not ionising

Question 4

What is the danger of visible light?

Answer 4

Can damage our eyes (e.g. we shouldn’t look directly into the sun)

Question 5

What are the dangers believed to be associated with the use of mobile phones? (4)

Answer 5

• Affects brain
• Headaches
• Fatigue
• Higher cancer risk

Question 6

What do the position of lines in the absorption spectrum show? (2)

Answer 6

If there is a shift and whether it’s red-shift or blue-shift

Question 7

Describe a solid in terms of Flow, Shape, Volume and Density (NB: density relative to a gas)

Answer 7

F= no
S= fixed
V= fixed
D= much higher than a gas

Question 8

Describe a liquid in terms of Flow, Shape, Volume and Density (NB: density relative to a gas)

Answer 8

F= yes
S= fits container shape
V= fixed
D= much higher than a gas

Question 9

Describe a gas in terms of Flow, Shape, Volume and Density

Answer 9

F= yes
S= fills container shape
V= can be changed
D= low compared to a solid/liquid

Question 10

Why do fluids rise when heated? (3)

Answer 10

• Fluids EXPAND when heated because particles move more
• So they take MORE SPACE
• DENSITY DECREASES, rises

Question 11

Why does the density of a fluid decrease when particles spread out?

Answer 11

The SAME MASS of fluid now occupies a BIGGER VOLUME

Question 12

Explain evaporation and the cooling effect this causes. Use the kinetic theory. (2)

Answer 12

• WEAK attractive FORCES between the liquid molecules

- FASTER molecules (w/ more Ek) break away and ESCAPE from liquid

Question 13

Why is the remaining liquid is cooler after evaporation has taken place?

Answer 13

Because the AVG. Ek of the remaining molecules has DECREASED

Question 14

What features does a car have to keep cool by design? (2)

Answer 14

• Radiator has a large SA,

- A cooling fan that switches on when engine= hot

Question 15

A motorcycle has cooling fins. What do these do to keep the engine cool?

Answer 15

-Inc. SA of the engine IN CONTACT WITH AIR so faster energy transfer

Question 16

How does a cooling fan cool the engine?

How does the large SA of the radiator in a car keep cool?

Answer 16

• Inc. AIR FLOW over radiator surface

- Inc. CONVECTION in the air and RADIATION

Question 17

What is a heat sink and what does it do? (3)

Answer 17

• A METAL PLATE
• Fixed to ELECTRONIC COMPONENT that turns off when too hot
• Inc. SA of the component

Question 18

How are household radiators engineered to transfer heat quickly? (3)

Answer 18

• Thin
• Flat
• May have fins

Question 19

Which is typically the most effective: A cavity wall, a solid brick wall, or a double glazed window? How would someone know this?

Answer 19

• A cavity wall

- Has the lowest U-value

Question 20

What does the rate of temperature change of a substance depend on? (4)

Answer 20

• The energy supplied to it
• Its mass
• Its SHC
• The material it’s made from

Question 21

How does a storage heater work? (3)

Answer 21

• Uses NIGHT electricity to heat special bricks inside
• ENERGY TRANSFER from bricks keeps room warm
• Bricks= high SHC so they store lots

Question 22

Why are non-metals insulators and not conductors?

Answer 22

ALL ELECTRONS HELD IN ATOMS

No delocalised electrons

Question 23

How does energy transfer take place in non-metals and what is this much less effective than?

Answer 23

• Atoms VIBRATE and shake each other

- Than energy transfer by free electrons