physics

Question 1

Why does a light bulb transfer energy to its
surroundings?

Answer 1

A bulb transfers energy to the surroundings by light waves and heating when a current flows through it because
the filament wire gets hot.

Question 2

Why does a light bulb get hot when a current
flows through it?

Answer 2

Electrons collide with the atoms inside it. These collisions happen because the filament wire has a property called resistance and we call the collision process resistive heating.

Question 3

Why are resistors useful components in
electric circuits?

Answer 3

• keep the current at safe levels
• heating devices

Question 4

What is voltage?

Answer 4

a measure of the energy transferred to (or from) the electrons

Question 5

How is voltage measured? What does the
measurement tell you?

Answer 5

Voltage is measured with a voltmeter, the unit is volts.
It tells us how much energy was transferred

Question 6

How does the voltage across the battery relate to the voltage across the components in a series circuit?

Answer 6

The voltage across the battery equals the total voltage of all of the components.

Question 7

What would the current voltage graph look
like for a resistor?

Answer 7

It would be a straight line through the origin. Because for a resistor voltage is directly proportional to
current.

Question 8

What would the current voltage graph look
like for different resistors?

Answer 8

The larger resistance the steeper the line would be on the graph because when the same current flows through a larger resistance more work will have to be done by the electrons

Question 9

What is resistance measured in?

Answer 9

Resistance is measured in ohms (Ω)

Question 10

How do you calculate the resistance of a
resistor?

Answer 10

Reistance = Voltage / Current (R = V/I)

Question 11

What is acceleration?
What is deceleration?

Answer 11

Acceleration is the rate that an object speeds up.
Deceleration is the rate an object slows down.

Question 12

What is the unit for acceleration?

Answer 12

m/s/s

Question 13

What does a speed time graph tell
us?

Answer 13

• A straight line tells us that the object is moving with constant acceleration.
• The steeper
  the line on a speed time graph the larger the object’s acceleration.
• A flat line on a
  speed-time graph tells us the object is moving at a constant speed.

Question 14

What happens to an object when a resultant force acts on it in the direction it is moving?

Answer 14

It accelerates and it’s kinetic store increases.

Question 14

What happens to an object when a resultant force acts on it in the direction it is moving?

Answer 14

It accelerates and it’s kinectic strore increases.

Question 15

What is the relationship between the size of an object’s acceleration and the resultant force acting on it?

Answer 15

Acceleration is directly proportional to resultant force.

Question 16

What does a graph of acceleration
against resultant force look like?

Answer 16

It would go straight through the origin

Question 17

What happens to an object when a resultant force acts on it in the opposite direction to its motion?

Answer 17

It will decelerate - its kinetic store will decrease and the thermal store of the surroundings will increase

Question 18

When you push an object, and then let go, why does it slow down?

Answer 18

there is a resultant
force acting on it in the opposite direction to its motion; like friction

Question 19

How do we stop moving vehicles?

Answer 19

We apply brakes, to apply a force in the opposite direction.

Question 20

Why do we stop moving vehicles
over a longer period of time?

Answer 20

As smaller deceleration’s require smaller resultant forces.

Question 21

Why do objects moving through air experience air resistance?

Answer 21

As the object collides with the air molecules.

Question 22

Why do larger surface areas and faster speeds result in more air resistance?

Answer 22

The larger the surface area of the object and the faster it is moving the more air molecules it will collide with per second

Question 23

What forces act on a falling object?

Answer 23

air resistance and weight

Question 24

What is terminal velocity?

Answer 24

When the falling object reaches a steady speed

Question 25

Why do falling objects reach terminal velocity?

Answer 25

the air resistance force will equal the weight and at this point there will be no resultant force so the object cannot accelerate any further

Question 26

What energy transfers take place in an object falling at terminal velocity?

Answer 26

its gravitational store is decreasing, the kinetic store stays the same and the loss from the gravitational store is transferred to the thermal store of the surrounding.

Question 27

What energy transfers take place in an object falling at terminal velocity?

Answer 27

its gravitational store is decreasing, the kinetic store stays the same and the loss from the gravitational store is transferred to the thermal store of the surrounding .

Question 28

How do we see things?

Answer 28

because light from that object reaches the retina at the back of our eyes

Question 29

What is the normal line?

Answer 29

The normal line is a dashed line drawn at 90 degrees to the surface of an object

Question 30

What is the law of reflection?

Answer 30

the angle of incidence = the angle of reflection

Question 31

What is the difference between diffuse and specular reflection?

Answer 31

- Specular reflection happens when light is incident on smooth surfaces. Parallel rays of incident light are reflected in a predictable way and remain parallel to each other upon reflection. - Diffuse reflection happens on rough surfaces. Parallel rays of light do not remain parallel to each other on reflection and are scattered in different directions.

Question 32

What is a virtual image? Why is it different to a real image?

Answer 32

A virtual image is one which the light rays appear to come but don’t actually come from the image e.g. the image seen in a mirror. A real image is one where the light rays do come from.

Question 33

What is refraction and why does it happen?

Answer 33

It happens because materials have different densities. It causes the wave to change direction.

Question 34

What effects does the refraction of light lead to?

Answer 34

Refraction of light at water/air boundaries causes objects to appear closer to the water than they actually are.

Question 35

What happens to parallel rays of light when they enter a convex lens?

Answer 35

They converge to the focal point

Question 36

What happens to parallel rays of light when they enter a concave lens?

Answer 36

They diverge away from the lens

Question 37

How are lenses used to correct eye defects?

Answer 37

They help the light focus on the retina. Short sighted - concave long sighted - convex

Question 38

What happens to white light when it is shone through a prism?

Answer 38

The seperate colours of the spectrum are seen

Question 39

What is the electromagnetic spectrum?

Answer 39

A family of transverse waves. R, M, I, V, U, X, G

Question 40

What are electromagnetic waves used for?

Answer 40

R - communication M - cooking I - security U - florescent light X - medical imaging G - sterilising

Question 41

Why are UV, X rays, and gamma rays dangerous?

Answer 41

Damage the structure of DNA.