Question

Draw a circuit diagram of an electric circuit containing a cell, a key , an ammeter, a resistor of 4Ω in series with a combination of two resistors (8Ω each) in parallel and a voltmeter across parallel combination. Each of them dissipate maximum energy and can withstand a maximum power of 16W without melting. Find the maximum current that can flow through the three resistors.  (3)

Answer 1

MAXIMUM CURRENT IN 4Ω  = √(P/R)
                                              
                                              =√16/4
                                             =√4 = 2A

MAXIMUM CURRENT IN 8Ω= 1/2 X 2 = 1A

Answer 2

hi,
power = 16 W

current (I) = ?

when resistance is 4  ohm

P = I² R
16 = I² ( 4 ) 
16/4 = I²
√4 = I
I = 2 A
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when resistance is 8 ohm

P = I² R
16 = I² ( 8 )
16/8 = I²
√2 = I
I = 1 A 

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HOPE IT HELPS