Electrical circuits

• What is current?

  Flow of electric charge (electrons).
• For current, 1) what is its unit and 2) how is it measured?

  Amps (A).

  Ammeter connected in series (main loop).
• What causes current to flow?

  Potential difference/voltage (from battery or power source).
• What is potential difference/voltage?

  A measure of energy transferred.
• For voltage, 1) what is the unit and 2) how is it measured?

  Volt (V).

  Voltmeter connected in parallel.
• What is resistance?

  A measure of how difficult it is for the current to pass through.
• What happens to the current if the voltage stays the same but resistance increases?

  It decreases.
• For resistance, 1) what is the unit and 2) how is it calculated?

  Ohms (Ω).

  Resistance = voltage / current.
• What factors affect resistance?

  Material, temperature, length of wire, thickness of wire.
• What is an ohmic conductor?

  A conductor where current is directly proportional to voltage (resistance stays the same).
• What happens to the temperature of a bulb when its current increases?

  Temperature increases.
• What happens to the resistance of a bulb when its temperature increases?

  Resistance increases.
• What is a diode?

  A diode only allows the current to pass through in one direction.
• What happens to the resistance of a thermistor as its temperature increases?

  Resistance decreases.
• What happens to the resistance of a LDR as light intensity increases?

  Resistance decreases.
• What is a series circuit?

  Series circuit made up of one loop (components are connected one after the other).
• What is a parallel circuit?

  Parallel circuits branch (made up of more than one loop).
• In a series circuit, what are the rules for:

  1)current,

  2)voltage,

  3)resistance.

  Current same every where.

  Voltage shared between components.

  Total resistance = sum of resistance of all components.
• In a parallel circuit, what are the rules for:

  1)current,

  2)voltage,

  3)resistance.

  Current sheared between branches.

  Voltage in each branch same as battery.

  Total resistance is less than resistance of lowest resistor.
• What is power and what are its units?

  Power is energy (J) supplied per second; units are watts (W).