I-V Characteristics

Question 1

Why is tungsten used in filament lamps

Answer 1

Because of a high melting point of 3000c

Question 2

How do tungsten filament lamps work

Answer 2

when a current goes through, it gets so hot, that it glows brightly

Question 3

What is the IV characteristic of a fixed resistor in a graph.

ie. what does curve/line look like

Answer 3

Straight line through the origin.

Question 4

What are the 2 type of methods of collecting data for IV characteristics

Answer 4

1. Vary the current flowing through circuit
2. Vary the PD in a circuit

Question 5

How to vary current or PD in a circuit.

Answer 5

1. Vary current by using variable resistor
2. Vary PD by using a potentiometer

Question 6

How does the circuit look like, when a potentiometer is used to vary the PD

Answer 6

The voltmeter is still in parallel, the ammaeter on left side and the component is connected with potentiometer in parallel by a wire into the potentiometer.

Question 7

What are the 3 IV characteristics of a fixed resistor

Answer 7

Resistance stays constant

it follows ohm’s law because current directly porportional to PD

The resistor behaves the same way regardless of polarity.

Question 8

What does a steep gradient represent in a IV graph represent, and what does a shallow gradient represent.

Answer 8

1. Steep gradient represents a low resistance
2. shallow gradient meaning lower gradient represents higher resistance

Question 9

What are the 3 IV characteristics of filament lamp

Answer 9

Resistance is not constant

Does not obey ohms law

Behaves in the same way regardless of polarity

Question 10

What can components be called that dont follow ohm’s law

Answer 10

non ohmic conductors

Question 11

How does a filament lamp work in terms of resistance?

8 steps

resistancce,current,pd,ions,electrons

Answer 11

1.The resistancce of filament lamp increases as the PD accross it increases.

2. Confirm this by determining V/I at diff points on graph
3. The increase in resistance is caused by wire getting so hot that it glows
4. As current increases so does the rate of flow of charge throuhg filament.
5. So more electrons per second pass through filament
6. So more collisions occur between electrons and positive metal ions per second
7. When electrons collide with ions they transfer energy to the ions
8. This causes ions to vibrate more. Ie. to increase in temperature and to collide with still more electrons.