Physics Yr 7 #1

Question 1

Why are Metals good conductors

Answer 1

Bc they contain electrons that are free

Question 2

Define thermal insulator

Answer 2

Insulators are poor conductors of heat, compared to thermals conductors. Eg wood

Question 3

Define thermal conductor

Question 4

Conduction

Question 5

Convection

Answer 5

• occurs only for liquids and gas

Convection current process:
1. Heat energy at the bott9m of the pan
2. water at the bottom will get hotter. So the particles move faster. So they move apart and become less dense.
3. Thus the hot water rises, bc it’s lighter.
4. The cooler, denser water sinks and takes its place.

Question 6

What is the Convection current process?

Answer 6

1. Heat energy at the bottom of the pan
2. water at the bottom will get hotter. So the particles move faster. So they move apart and become less dense.
3. Therefore the hot water rises, bc it’s lighter.
4. The cooler, denser water sinks and takes its place.

Question 7

What are the 3 pathways of heat transfer

Answer 7

Conduction, convection, radiation

Question 8

How do particles conduct heat

Answer 8

Particles transfer energy by colliding with other particles when they vibrate.
Energy transfer happens until the two surfaces are the same temperatures.

Question 9

What is power

Answer 9

Power is the measure of how fast energy is transferred from one form to another

Question 10

Definition of the waves

Answer 10

Peak top of a wave
Trough bottom of a wave
Frequency the number of waves passing a point each second
Amplitude the distance between the origin and the peak/trough
Wavelength the distance between one whole wave(2peaks and 2trough)

Question 11

Transverse and longitutial

Answer 11

Transverse is the direction of the wave is a right angle to the movement of the source
Longitutial is the direction of the wave is parallel to the movement of the source

Question 12

Define Vacuum

Answer 12

Space with no particles or air

Question 13

Every hot object will emit …… (fill in the gap)

Answer 13

Radiation / Infrared radiation / thermal radiation / heat

Question 14

Radiation travels as ……..

Answer 14

Waves

Question 15

Can conduction and convection happen in space?

Answer 15

No , bc they involve particles, unlike radiation. In space there are no particles or air .

Question 16

What objects give out / emit radiation?

Answer 16

All objects (including you)

Question 17

Describe 2 factors that determine how much infrared radiation is emitted

Answer 17

1. The type of radiation depends on their temperature.
2. How much radiation they emit per second depends on the type of surface.

Question 18

What do the words transmitted, absorbed and reflected mean?

Answer 18

Transmitted: a wave passed through or across a material (medium)

Absorbed: Energy is ‘taken-in’ by the material and the internal energy of the material will increase

Reflected:

Question 19

tell me 3 things that detect infrared radiation?

Answer 19

1. skin
2. thermal imaging camera
3. remote thermometer

Question 20

dark colours ……. IR
light or shiny colours …… IR

Answer 20

absorb
reflect

Question 21

what direction does radition travel in

Answer 21

in all directions in a straight

Question 22

give 2 uses of radiation

Answer 22

1. infrared photographs
2. remote controls
3. heat seeking missiles
4. seaching for earthquake surviors
5. chasing criminals
6. making toast
7. keeping homes warm

Question 23

how to slow down convection. give me an example

Answer 23

use materials that contain pockets of air which cannot move.

eg. foam in between the walls of your house

Question 24

temperature affect the rate of energy transfer. conduction, convection or radiation?

Answer 24

all 3!

Question 25

Pinna

Answer 25

Pinna also known as the outer ear is the visual part of our ear. It is made from flexible cartilage covered by our skin which comes in different shapes and sizes. It’s job is to carry sound waves from the air and direct them to the ear canal

Question 26

Ear drum

Answer 26

Y
The ear drum is like a barrier to our ears. It is very thin and delicate and is located at the back of our ear canal. When sound waves travel through the air and into the ear the eardrum will vibrate. These vibrations are essential cuz it helps travel sound further into our ear

Question 27

Ossicles

Answer 27

The ossicles are made out of 3bones. These bones will amplify the vibrations to ensure the sound signals get stronger when they travel from the eardrum to the inner ear

Question 28

Cochlea

Answer 28

When the amplified sound from the ossicles to the cochlea it will go through a fluid filled tunnel. Inside the tunnel thousands of tiny hair like cells will start moving. Specific hairs will move though. Like a high pitch sound some hairs will move and low pitch sounds another set of hairs will move. This creates electrical signals like messages to your brain.