3.5.1.2 - Current-Voltage Characteristics Flashcards Preview

AS Physics > 3.5.1.2 - Current-Voltage Characteristics > Flashcards

Flashcards in 3.5.1.2 - Current-Voltage Characteristics Deck (19)
Loading flashcards...
1
Q

What is an ohmic conductor?

A

The current is directly proportional to the potential difference.

2
Q

When does an ohmic conductor produce a straight line on a graph of I against V?

A

When the physical conditions, such as temperature remain constant.

3
Q

What is the circuit symbol for a variable resistor?

A

A rectangle with an arrow pointing towards the right hand corner through the rectangle.

4
Q

Describe the two graphs for an ohmic conductor?

A

Both straight lines through the origin, however the V/I graph is shallower.

5
Q

Describe the two graphs for a filament lamp.

A

I/V is the shape of an s, through the origin.

V/I opposite to I/V graph, curves upwards once past the origin.

6
Q

What happens to the resistance in metal filament?

A

Increases as the temperature increases. This is because ions in the metal filament vibrate more as the temperature increases, resisting the passage of electrons to a greater extent.

7
Q

What is the filament lamp an example of?

A

A non-ohmic conductor.

8
Q

Why aren’t semiconductors as good at conducting electricity?

A

There are far fewer charger carriers available.

9
Q

When and why are more charge carriers released to semiconductors.

A

If energy is supplied to the semiconductors, more charge carriers can be released. This means they make excellent sensors for detecting changes in their environment.

10
Q

What are the two types of semi conductors?

A

Thermistors and diodes.

11
Q

What is a thermistor?

A

A resistor with a resistance that depends on its temperature.

12
Q

What happens as resistance is increased in a NTC thermistor?

A

The resistance decreases as the temperature goes up.

13
Q

Describe the two graphs for a thermistor?

A

The I/V graph is a reverse of an s. After the origin it curves upwards.
The V/I graph is shaped like an s.

14
Q

What happens when you warm a thermistor?

A

It gives more electrons enough energy to escape from their atoms. This means that there are more charge carriers available, so the resistance is lower.

15
Q

Describe the symbol of a thermistor.

A

Rectangle with a horizontal line underneath which then crossed through the rectangle towards the right hand corner.

16
Q

What do diodes to?

A

They are designed to let current flow in one direction only.

17
Q

What is forward bias?

A

The direction in which the current is allowed to flow.

18
Q

What is reverse bias?

A

The resistance of the diode is very high and the current that flows is negligible.

19
Q

Describe the symbol for a diode.

A

Triangle pointing towards the right with a vertical line at the end of the triangle.