Even more logical

Question 1

What are used in potential divider circuits?

Answer 1

Switches, LDRs and thermistors are used in a potential divider circuit to make the input to a logic gate high.

Question 2

When the switch is:

Answer 2

• Open, the input to the logic gate is low.
• Closed, the input is connected directly to the 5 V supply. The input is high.
• The LDR and thermistor work in a similar way.

Question 3

How does a relay work?

Answer 3

• When a current passes through the coil, the iron armature is attracted.
• The armature pivots and pushes an insulating bar against the central contact.
• The central contact moves, opening the normally closed contacts and closing the normally open contact.

Question 4

How are logic gates used in relays?

Answer 4

Current output from logic gates is low but it can be passed through a relay to switch on a larger current needed for motors, heaters etc.

Question 5

What else does the relay do to the logic gate?

Answer 5

The relay also isolates the logic circuits from the high current to avoid damage to the logic gates.