An electric iron of resistance `20 Omega` takes a current of `5 A`. Calculate the heat developed in `30 s`.

(a) what is menat by the heating effect of current ? State three factors on which the heat produced in a wire by an electric current depends. (b) Explain why, through the heating element of an electric heater glows, but its connecting cord does not l glow. ( c) An electric geyser of resistance 20 Omega takes a current of 5 A. calculate the heat produced in 2 minutes. (d) Name the commercial unit of electric energy. How many joules are equal to this unit ?

(a) Write down the formula for the heat produced when a current I is passed through a resistor R for time t. (b) An electric iron of resistance 20 ohms draws a current of 5 amperes. Calculate the heat produced in 30 seconds.

An electric bulb of resistance 400 Omega , draws a current of 0.5 A . Calculate the power of the bulb and the potential difference at its ends.

An electric heater of resistance 8 Omega draws 15 A from the service mains for 2 hours. Calculate the rate at which heat is developed in the heater.

A galvanometer of resistance 30 Omega shows a full scale deflection for a current of 2 mA. Calculate the value of resistance required to convert it into a voltmeter of range 0-5 volt.