8.5 Resistance

Question 1

What’s resistance, unit

Answer 1

Measures opposition of material to the flow of current
Ohm (Ω)

Question 2

Resistance of conductors and insulators

Answer 2

Low, high

Question 3

Relationship between resistance and current
Why

Answer 3

Higher resistance smaller current
stronger opposition to flow of current

Question 4

Factors affecting resistance

Answer 4

Materials, thickness, length

Question 5

thickness, length w higher resistance

Answer 5

Thin, long
幼、長；傳電慢

Question 6

Whats resistor
Use

Answer 6

Circuit component w fixed value of resistance
Control/limit current

Question 7

Whats rheostat

Answer 7

Circuit component whose resistance can be adjusted

Question 8

Rheostats types, how it works

Answer 8

Sliding rheostat: move sliding contact, length of resistance wire current flows through changes, resistance changes thus the current

Rotary-type rheostat: rotate sliding contact….

Question 9

Sliding rheostat

Answer 9

Sliding contact to the right increases length of resistance wire
Rheostat resistance higher, current smaller

Question 10

Rotary type rheostat devices

Answer 10

Dimmer switches, hi-fi volume control
Adjust current thus brightness