2.2 - Modelling and Measuring Electricity

Question 1

What is Ohm’s law?

Answer 1

• States that as long as temperature remains the same, the resistance of a conductor stays constant,
• That the current is directly proportional to the voltage applied (voltage increase = current increase).
• Ohm’s law also states that if the temperature of a resistor changes, the resistance also changes.
• Resistance will be low when the resistor is cool and high when the resistor is warm.

Question 2

What is the formula for voltage?

Answer 2

Voltage = Current x Resistance (V=I x R)

Question 3

What is the formula for current?

Answer 3

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

Question 4

What is the formula for resistance?

Answer 4

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

Question 5

What are the units for voltage, current, and resistance, respectively?

Answer 5

VOltage: volts (V)
Current: amperes (A)
Resistance: Ohms (Ω)

Question 6

Fill in the blanks.
1 amp = ___________
1 volt = ___________

Answer 6

1 amp = 1000 milliamperes

1 volt = 1000 millivolts

Question 7

List the different types of meters and what they are used for.

Answer 7

• Voltmeters - Measure the voltage difference (voltage drop) across a device
• Millivoltmeters - Used for small voltages
• Ammeters - Measure current in amps
• Galvanometers - Used for measuring small currents
• Multimeters - Measure voltage, current, and resistance in a circuit

Question 8

What are different resistors used for?

Answer 8

Different resistors are used for different applications

Question 9

WHat are the 2 most common resistors?

Answer 9

The two most common resistors are the wire wound and carbon-composition