(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.

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Solution

(a) H = I²Rt where H is the heat energy produced, I is the current, R is the resistance and t is the time.
(b) I = 5 A, R = 20 Ώ and t = 30 s
H = I²Rt = 5² x 20 x 30 = 25 x 20 x 30 = 15000 J

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Q. Electric iron of resistance 20 ohm draws a current of 5 ampere.
Calculate the heat developed in 30 seconds .

My solution
H=I^2 Rt
H= (5^2 × 20 × (30÷3600))
H= 500×1÷120

Is it correct ??

The heat produced by passing an electric current through a fixed resistor is proportional to the square of :
(a) magnitude of resistance of the resistor
(b) temperature of the resistor
(c) magnitude of current
(d) time for which current is passed

An electric iron of resistance $20 Ω$ takes a current of $5 A$ . Calculate the heat developed in $30 s e c o n d s$ .

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(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.

(a) H = I2Rt where H is the heat energy produced, I is the current, R is the resistance and t is the time. (b) I = 5 A, R = 20 Ώ and t = 30 s H = I2Rt = 52 x 20 x 30 = 25 x 20 x 30 = 15000 J

(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.

(a) H = I²Rt where H is the heat energy produced, I is the current, R is the resistance and t is the time.
(b) I = 5 A, R = 20 Ώ and t = 30 s
H = I²Rt = 5² x 20 x 30 = 25 x 20 x 30 = 15000 J