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)
ii)
iii)
Power, P = V.I.
= I2R
= (0.5)2 x 3
= 0.25 x 3
P = 0.75 Watt
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) 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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