Long Answer TypeThe figure shows a new circuit. [Page 589]
When the circuit is switched on the ammeter reads 0.5 A.
i) Calculate the value of the unknown resistor R.
ii) Calculate the charge passing through the 3 ohm resistor in 120 s
iii) Calculate the power dissipated in the 3 ohm resistor.i) Name the devices used to protect the electric circuits from overloading and short circuits.
ii) On what effect of electricity does the above device work?i) An electrical gadget can give an electric shock to it’s user under certain circumstances. Mention any two of these circumstances.
ii) What preventive measure provided in a gadget can protect a person from an electric shock?i) The two circumstances are as follows:
1. An electric shock may be caused either due to poor insulation of wires.
2. When the electric appliances are touched with wet hands.
ii) As preventive measures, the insulation of wires must be of good quality and it should be checked from time to time particularly, when they become old, so that no wire is left naked.
i) Draw a simple labelled diagram of a d.c. electric motor?
ii) What is the function of the split rings in a D.C motor?
iii) State one advantage of a.c. over d.c.?
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