Resitivity

Question 1

what is the relationship between length and resistance

Answer 1

they’re directly proportional

Question 2

what is the relationship between cross-sectional area and resistance

Answer 2

they’re inversely proportional

Question 3

what is resistance

Answer 3

Resistance is the property of a specific object (like a wire) that resists electric current. It depends on the material, length, and thickness of the object.

Question 4

what is resistivity

Answer 4

Resistivity, on the other hand, is a property of the material itself, no matter its size or shape. It tells how much the material naturally resists the flow of electricity.

Question 5

how would you determine resistivity of a metal

Answer 5

complete circuit - power supply, ammeter and variable resistor in series with wire. voltmeter in parallel with the wire, with a crocodile clip on wire, with the wire connecting to the voltmeter.

• attach the crocodile clip to the wire to complete the circuit.
• start at 20cm as shorter = no resistance = very hot/could burn (safety hazard)
• ensure current is below 1A to avoid heating
• record pd across wire and current, calculate resistance using ohms law
• plot graph R-L
• find the cross-sectional area of the wire by measuring the diameter in 3 different places using a micrometer and use formula pi r squared
• dependent: resistance
• independent: length
• ## control: same wire, same temp, similar current and same material