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Phys Paper 1 > P4: Electric Circuits > Flashcards

P4: Electric Circuits Flashcards

1
Q

What is an electric current?

A

The rate of flow of electrons in a circuit

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2
Q

What happens when the electrons from the current pass through the lamp?

A

Electrons carry energy and pass it to the components of the circuit, where the electrical energy is transferred to light energy and thermal energy

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3
Q

What is the conventional current?

A

Many years go, scientists thought the electric current flowed from the positive end of the cell to the negative, this is still represented on a circuit diagram, called the conventional current

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4
Q

What is a series circuit?

A

The current can only flow in one path along the circuit

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5
Q

What is the measure of current?

A

Amps, using an ammeter

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6
Q

What is the current like in a series circuit?

A

The same all around
I1=I2=I3

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7
Q

What is a parallel circuit?

A

A circuit which contains ‘branched’ wires

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8
Q

What is the current like in a parallel circuit?

A

Current in the branches = total current leaving the cell

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9
Q

What is potential difference/ voltage?

A

Voltage of 1 tells us that 1 joule of energy is transferred for each coulomb of charge that is moving through the circuit
The pressure from an electrical circuit’s power source that pushes electrons (current) through a circuit

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10
Q

How is voltage measured?

A

Using a voltmeter

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11
Q

What is the voltage like in a parallel circuit?

A

Same throughout
V1=V2=V3

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12
Q

Why would two lamps be dimmer when attached in series?

A

Total energy carried by the current is shared between the two lamps

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13
Q

What is the voltage like in a series circuit?

A

Total potential difference across the circuit is equal to the potential difference supplied by the cell

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14
Q

What is a battery?

A

More then one cell joined together in the same direction

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15
Q

What is the potential difference across a battery?

A

The sum of potential difference across all its cells

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16
Q

What is electrical charge?

A

The size of the electric current is the rate of flow of electrical charge
Current of 1 amp = 1 coulomb of charge per second

17
Q

What is the formula for charge flow?

A

Q = It
Charge flow (C) = current * time (s)

18
Q

What is the formula for energy transferred?

A

E = QV
Energy transferred (J) = Charge flow (C) * Voltage (V)

19
Q

Describe current flow through a wire

A

An electric current is a flow of electrons through a conductor such as a metal wire. As they move, electrons collide with atoms in the metal , electrical energy is transferred into other forms

20
Q

What is resistance?

A

The potential difference required to drive a current through a component

21
Q

What is the formula for resistance?

A

V = IR
Voltage = Current * Resistance
(V) (A) (Ω)

22
Q

What is a resistor?

A

A circuit component that increases the resistance

23
Q

What is an ohmic conductor?

A

A resistor whose current is directly proportional to its voltage, provided all physical conditions remain constant

24
Q

What happens to the filament in a filament lamb as an electric current passes through it?

A

It gets hotter (causing it to glow)

25
Q

What is the graph like for a filament bulb and why is this?

A

Almost directly proportional, with curved ends.
As the current increases, so does the temperature. resulting in a higher resistance

26
Q

What is a diode?

A

A component which only lets current flow in one direction, as it has very high resistance on the other end

27
Q

What is the graph like for a diode?

A

No current passes in the reverse direction
Forward direction, current increases as p.d. increases

28
Q

What are LEDs?

A

A diode which lets out light when a current flows through

29
Q

What is resistance like in a series circuit?

A

Resistors in series add together e.g. R1 = 100Ω + R2 = 50Ω = R3 = 150Ω

30
Q

What is resistance like in a parallel circuit?

A

Total resistance is less than the smallest resistance in the circuit. This is because there are more than 1 pathways for a current to take, meaning more current will flow through the resistors

1/R1 + 1/R2 = 1/R3

31
Q

How does LDR resistance change with light?

A

Light - Low resistance
Dim - High resistance

32
Q

How does thermistor resistance change with temperature?

A

Phys Paper 1 (8 decks)

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