Controlling Circuits

Question 1

What are LDRs?

Answer 1

Electrical devices that change resistance according to light levels.

Question 2

LDRs can be used as _______ sensors and are usually 150 _____ in bright light and 10 megaohms in complete ____________

Answer 2

Light
Ohms
Darkness

Question 3

We can use components that change ___________ when external factors change, such as _______ or temperature, to control __________

Answer 3

Resistance
Light
Circuits

Question 4

In LDRs, as voltage and light level increases, the resistance ____________

Answer 4

Decreases

Question 5

Light allows _________ electrons to flow through an LDR

Answer 5

More

Question 6

Heating metal raises their ____________. The __________ electrons find it ________ to flow when the positive metal ions vibrate more.

Answer 6

Resistance
Delocalised
Harder

Question 7

Increasing the temperature give the semiconductors electrons _________ energy

Answer 7

More

Question 8

Semiconductors-
Some of the materials electrons gain enough energy to _______ them, allowing them to flow when a potential ____________ is applied.

This ___________ the resistance

Answer 8

Free
Difference
Decreases

Question 9

A negative ______________ coefficient (NTC) thermistor contains a semiconductor. As it’s temperature __________, its resistance decreases. A ___________ can be used as a switch in a circuit

Answer 9

Temperature
Increases
Thermistor