To Assemble a Household Circuit Comprising Three Bulbs, Three (on/off) Switches, a Fuse and a Power Source
Aim
To assemble a household circuit comprising three bulbs, three (on/off) switches,a fuse and a power source.
Apparatus and material
Apparatus:
No apparatus required in assembling a circuit.
Material:
Three bulbs (6 V, 1W) each, fuse of 0.6 A, main switch a power supply (battery . eliminator), three (on/off) switches flexible connecting wire with red and black plastic covering,a fuse wire.
Supplementary:
Main electric board with a two-pin socket and main switch.
Theory
Electricity supplied to us for domestic purposes is 220 V A.C. and 50 Hz. The household circuit, all appliances are connected in “parallel” with mains. The switches are connected in series with each appliances in live wire. 5 A switches are required for normal appliances like, bulbs, fluorescent tubes fans etc. 15 A sockets and switches are required for heavy load appliances ‘ like, refrigerator, air conditioner, geyser, hot plates etc. All appliances must have three wires called live, neutral and the earth. Total power consumption ‘P’ at a time
P = P
1
+ P
2
+ P
3
+………..
where P
1
, P
2
, P
3
are the powers drawn by appliances.
To protect the appliances from damage when unduly high currents are drawn fuse of little higher rating, 10 to 20% higher than the current normally drawn by all appliances. For further safety, a suitable value MAINS FUSE like rating 32 A is connected in series with supply source.
Diagram
Procedure
- Connect the bulbs B 1 , B 2 and B 3 in series with switches S 1 , S 2 and S 3 respectively and connect each set of B-S in parallel with each other.
- Connect main supply to a step-down transformer (battery eliminator) to get required voltage from 0 to 10 V (0, 2, 4, 6, 8 and 10 V).
- Connect the mains fuse M.S. in series with the power supply (battery eliminator).
- Connect an A.C. ammeter in series with the B-S set.
- Connect one end of power supply to one end of B-S set.
- Check the circuit one again to ensure that household circuit is complete.
- Gradually increase the current to 0.75 A, the fuse must bum off at about 0.6 A.
Physics Lab Manual NCERT Solutions Class 12 Physics Sample Papers