# Electricity And Energy Flashcards

1
Q

What is the Current?

A

The current is the rate of flow of charge.

2
Q

What is the current in a circuit measured using?

A

An Ammeter.

3
Q

What is Direct Current?

A

Direct Current moves in one direction only (from negative to positive) and the size of the current is constant in size and direction.

4
Q

Where is DC usually supplied from?

A

A battery.

5
Q

What is Alternating Current?

A

Alternating current constantly changes size and direction.

6
Q

Where is AC usually supplied from?

A

The Mains.

7
Q

What is the Mains Supply in the UK?

A

230 Volts.

8
Q

What is the Voltage?

A

Voltage is the energy supplied per unit charge.

9
Q

What is Voltage measured by?

A

A Voltmeter.

10
Q

How must a voltmeter be connected in order to measure the voltage across a component?

A

In parallel with the component.

11
Q

In what type of circuit is the current the same at all points?

A

A Series Circuit.

I1=I2=I3

12
Q

In which type of circuit is the Voltage shared between components?

A

A Series Circuit.

Vs=V1+V2

13
Q

In which circuit does the current split between branches?

A

In a Parallel circuit.

I1=I2+I3

14
Q

In which circuit is the voltage equal across each branch?

A

In a Parallel Circuit.

Vs=V1=V2

Note: The voltage across each branch is equal but the voltage across components on one branch will not always be equal.

15
Q

What is the resistance like in a series circuit?

A

In a series circuit the total resistance is equal to the sum of the resistance of each component.

Rt= R1+R2

16
Q

What is the resistance like in a parallel circuit?

A

1/Rt=1/R1=1/R2

This means that when resistors are added in parallel the total resistance in the circuit decreases.

17
Q

What is the power rating of an appliance?

A

The power rating of an appliance is the energy it transfers per second.

18
Q

What is a fuse?

A

A fuse is a safety device which will stop current flowing if the current becomes too high. This avoids appliances overheating and starting fires.

19
Q

Is an appliance has a power rating of over 720 watts which type of fuse will it contain?

A

A 13A fuse

20
Q

If an appliance has a power rating below 720W what type of fuse will it contain?

A

A 3A fuse.

21
Q

Why is a resistor connected in series with an LED?

A

To limit the current in the LED.

22
Q

What is a Transistor?

A

A transistor is a voltage-controlled switch.

23
Q

The voltage across which resistor determines whether the transistor turns on?

A

The voltage across the bottom resistor.

24
Q

How does light affect the resistance of an LDR?

A

If the light level decreases, the resistance of the LDR will increase, therefore the voltage will increase.

If the light level increases, the resistance of the LDR will decrease, therefore the voltage will decrease.

25
Q

What is a capacitor?

A

Capacitors are used in circuits where there is a time delay. Capacitors can be used in switching circuits to turn on a component after a certain time period.

26
Q

What is a Relay Switch?

A

Relay switch can be used in a low voltage circuit to turn on a high voltage appliance in a separate circuit.

27
Q

What is pressure?

A

Pressure is the force applied per unit area.

28
Q

How does decreasing the surface area affect the pressure applied?

A

As the surface area decreases the pressure increases.

29
Q

What is the pressure of a gas?

A

The total force exerted by the particles over the surface area of the container.

30
Q

How does temperature affect kinetic energy?

A

The higher the temperature the faster the particles will move.

31
Q

What is Boyles law?

A

P1V1=P2V2

As long as there is no change in temperature.

32
Q

How do you change degrees Celsius into kelvins?

A

You add 273 to the value.

33
Q

How does temperature affect pressure?

A

As the temperature of a gas increase, the particles begin to move with a higher velocity. This means that the particles will collide with the container walls more times a second and with greater force. The volume of the container stays constant and therefore the pressure must increase.

34
Q

How does Volume affect pressure?

A

As the temperature of a gas increases the particles begin to move with a higher velocity. This means that the particles will collide with the container walls more times a second and with a greater force. Since P=F/A l, the volume must increase to the keep the pressure constant.

35
Q

When describing the kinetic model of gases what is it a good idea to mention?

A
1. Temperature
2. Speed of particles
3.Kinetic energy of particles
3. The frequency of the collision with the container walls
4. Force in the walls of the container
5. Pressure