Physics

Question 1

What is electric current

Answer 1

Electric current is the flow of charge around a circuit

Question 2

Can circuits’ energy flow if their incomplete?

Answer 2

No, a circuit had to be complete to work

Question 3

What are the moving charges?

Answer 3

The moving charges in a circuit are negative electrons

Question 4

What is convention current?

Answer 4

Conventional current is electron current which behaves as though it is positive charges that causes current flow, because it travels from the positive terminal to the negative, where as regular charge flows the opposite way

Question 5

Is current ever used up?

Answer 5

No, current is never used up as it flows through s constant circuit. The total current in the circuit is always the same

Question 6

What is potential difference across a circuit?

Answer 6

Potential difference in a circuit is the energy that flows between two points in a circuit

Question 7

How is potential difference measured?

Answer 7

Potential difference is measured in volts, and if you add the voltage of each component in series, that gives you the voltage of the whole power supply

Question 8

How do you calculate potential difference?

Answer 8

Potential difference can be calculated across a component using ohms law:
Potential difference (V)= current (I)xresistance(R)

Question 9

How is ohms law applicable to current and resistance?

Answer 9

Ohms law can be applied to both current and resistance as follows:
Current (I)=potential difference (V) ÷ resistance (R)
Resistance=potential difference (V) ÷current (I)

Question 10

What is resistance in a circuit?

Answer 10

Resistance is anything in a circuit that slows down the flow of current.

Question 11

What is resistance measured in?

Answer 11

Resistance is measured in ohms (Ω)

Question 12

What does resistance mean in a circuit?

Answer 12

In a circuit as long as the potential difference stays the same, the higher the resistance of a component, the smaller the current that flows through it.

Question 13

What do you call components and materials that electricity can pass through?

Answer 13

Conductors. Metals are the best form of these.

Question 14

What are insulators?

Answer 14

Insulators are components or materials that don’t easily allow electricity to pass through them if at all (like wood).

Question 15

Why are insulators good heat stores?

Answer 15

Because they trap the heat energy in itself as they do not allow free electrons to pass through them and transfer energy easily like conductors. So good conductors of electricity are bad ones of heat.

Question 16

How can you tell which components in a circuit are better conductors?

Answer 16

The lower the resistance of a component, the better it is at conducting electricity because more electrons are being permitted to pass through easily.

Question 17

What is the role of ammeters in a circuit?

Answer 17

Ammeters measure electric current around the circuit.

Question 18

What is current measured in?

Answer 18

Current is measured in amperes (amps for short). You measure the current through a circuit by inserting the ammeter into the battery and the bulb. But because current didn’t get used up, the current through the ammeter’s the same as through the bulb

Question 19

What is used to measure potential difference?

Answer 19

To measure potential difference voltmeters are used. Potential difference is measured across something in a circuit like a bulb.

Question 20

What are potential difference ratings in batteries and bulbs?

Answer 20

A battery potential difference rating tells you the potential difference it will supply across the circuit. A bulb rating tells you the maximum potential difference that you can safely put across it for it to work.

Question 21

What is a series circuit?

Answer 21

A series circuit is a circuit where the current has no choice of route and every part of the circuit is on the same path.

Question 22

Can any part of s series circuit be on or off at a given time?

Answer 22

In series circuits the current is either on or off- the switch being open or any other break in he circuit will stop the current flowing everywhere, like in fairy lights

Question 23

Is the current different in any part of a series circuit?

Answer 23

No, the current in a series circuit is the same throughout the circuit as the current has no choice of route, which is another reason why the circuit breaks if one component is lost.

Question 24

How is potential difference portrayed in the battery (or cell) of a series circuit?

Answer 24

In series circuits, the potential differences across each of the components add up to the total potential difference of the whole cell.

Question 25

What are parallel circuits?

Answer 25

In parrallel circuits, the current has a choice of where it is distributed across the circuit

Question 26

Why will ammeter readings in a parallel circuit be different to eachother?

Answer 26

Because when current in a parallel circuit flows out of the cell and through the first ammeter, it may have two or three different directions it can travel to distribute current, so if you have 3 bulbs and five ammeters the readings on each are different to eachother

Question 27

What happens to the dum of the current after it has passed through multiple bulbs in a parallel circuit?

Answer 27

When current has been distributed across each bulb and it has been read on each ammeter, the overall current passing from each bulb meets up at the end of the circuit at one individual ammeter, so the sum of the ammeter’s readings on the bulbs will equal the amount on the ammeters at the end

Question 28

Can some bulbs in a parallel circuit be on and the others be off?

Answer 28

Yes, if the bulbs have switched you can open the switch to a bulb (which severes the current flowing through it) and the other bulbs would still remain on with their switches closed because the current has a choice of where to glow still

Question 29

Is the potential difference in each bulb in a parallel circuit still equal to the potential difference in the cell like in a series circuit?

Answer 29

Yes, even the bulbs that are turned off in a parallel circuit still have a potential difference output, so the sum won’t be thwarted

Question 30

What is static electricity?

Answer 30

a stationary electric charge, typically produced by friction within negatively charged electrons and postitively charges protons, which causes sparks or crackling or the attraction of dust or hair.

Question 31

What is gravity?

Answer 31

Gravity is the force that attracts a body towards the centre of the earth, or towards any other physical body having mass. That is why planets such as the earth and moon are in orbit to the sun- they are attracted by gravity. The larger the object, the stronger the force of gravity( that’s why planets with a large mass have higher gravity). Also, the longer the distance between objects the weaker the gravitational attraction becomes.

Question 32

What is mass?

Answer 32

Mass in objects is the amount of matter in an object without any forces or anything acting on it. The mass of an object never changes, no matter where in the universe it is.

Question 33

What is weight caused by?

Answer 33

The pull back of gravity

Question 34

Does an object retain its weight no matter the planet it’s on?

Answer 34

An object has the same mass whether it’s on earth or any other planet, but it’s weight will be different according to the gravitational pull of that planet or star.(eg: something weighing 1kg will weigh less on mars (about 3.7N) than on earth (about 10N) because the force of gravity pulling on it is less.

Question 35

What is weight?

Answer 35

Weight is a force motivated by gravity which is measured in Newtons (N). It’s measured using a spring balance or newton meter.

Question 36

Is mass a force?

Answer 36

Mass is not a force. It’s measured in kilograms (kg) with a mass balance which stays the AMA won any planet

Question 37

What is the formula for calculating weight?

Answer 37

Weight=mass+gravitational field strength W=mXg ( the weight is in newtons, the mass in kilograms and the gravitational field strength is in Newton kilograms (N/kg))

Question 38

What is the weight in newtons of a 5kg mass both on earth and mars?(weight formula example)

Answer 38

A: W=mXg On earth: W= 5 x 10= 50N(the weight of the kg mass is 50N) On Mars: W= 5 x 3.7= 18.5N ( the weight of the 5kg mass is 18.5N)

Question 39

What is sound?

Answer 39

A sound wave is the pattern of disturbance caused by the movement of energy traveling through a medium (such as air, water, or any other liquid or solid matter) as it propagates away from the source of the sound. The source is some object that causes a vibration, such as a ringing telephone, or a person's vocal chords

Question 40

What are longitudinal waves?

Answer 40

Longitudinal waves have vibrations that are parallel to the direction of the sound wave. This means the vibrations are also parallel to the the direction of energy transfer

Question 41

What are examples of longitudinal waves?

Answer 41

1. Sound waves | 2. A slinky spring when you push the end( because there are vibrations in the same direction as the wave is travelling)

Question 42

How does sound travel?

Answer 42

Sound travels as a longitudinal pressure wave

Question 43

What are sound waves caused by?

Answer 43

Vibrating objects

Question 44

What does sound need to travel?

Answer 44

Sound needs a medium ( eg: air or water) to travel through because something has to pass on the sound vibrations.

Question 45

How are the sound vibrations passed through the medium?

Answer 45

Via a series of compressions ( regions of squashed up particles)

Question 46

Why can’t sound travel in space?

Answer 46

Sound can’t travel in space because it’s mostly a vacuum so there are no particles to act as a medium