a room heater is connected in serise with a 100w bulb.if the
100w bulb is replaced by a 40w bulb then the output of the
heater is increase/decrease/remain same?
Answers were Sorted based on User's Feedback
Answer / vivek anand
Let us understand by taking some example.
let say heater is of 500w and 250v
Bulb 100w and 250v
now, calculate the R
P = V^2/R
SO
R = V^2/P
R1 (heater) = 250 * 250 /500 = 125 ohm
R2 (bulb)= 250 * 250 /100 = 625 ohm
Now, as the question says, they are connected in series, lets find out the current drawn by the circuit
I = V/R
LET THE CIRCUIT CONNECTED WITH 250V SUPPLY
I = 250/(125+625) (R ARE IN SERIES)
I = 0.33A
THIS IS THE AMOUNT OF CURRENT DRAWN BY CIRCUIT IN CONFIGURATION 1.
power of heater = I^2*R*T (TAKE T = 1 hr)
P = 0.33*0.33*125*60*60 = 495 ~ 500w
Now, replace 100w bulb with 40w bulb
R2 (bulb)= 250 * 250 /40 = 1562.5 ohm
New Resistance of circuit will be
R'= 125 + 1562.5 = 1687.5
**NOTE "THE CURRENT IN SERIES IS ALWAYS SAME" and "THE CURRENT DRAWN BY THE CIRCUIT DEPENDS ON LOAD (RESISTANCE)"
In this case we change the load form 750 ohm to 1687.5 ohm, so definitely the current drawn will change.
Now, I' = 250/1687.5 = 0.148 A
now this current will same in the circuit for both bulb and heater bcoz they are in series.
NEW POWER OF HEATER
P = 0.15*0.15*125*60*60 = 101.25
so
OUTPUT DECREASES
Is This Answer Correct ? | 54 Yes | 7 No |
Answer / sarfraj palegar
in this condition heater output will increases
lets take a example and heater resistance X ohms
voltage =current*resistance
in first condition resistance in cercuite is high thats why
current low compare to 2nd condition
in 2nd condition this higher current passes throug circuit
as per formula of heat
H=I2RT
heat output will increases
Is This Answer Correct ? | 3 Yes | 7 No |
Answer / syed ali raza naqvi
output same because in series current is same.in every
point and voltages different.
Is This Answer Correct ? | 6 Yes | 11 No |
Answer / roopesh
P=(I^2)R
In series circuit the current is same. So in series circuit power(p) is proportional to resistance(r), therefore 100w bulb has more resistance compare to 40w bulb.
Is This Answer Correct ? | 0 Yes | 5 No |
Answer / alok das
If the 100w buld is replaced by a 40w buld then the output
of the heater is increase.
Is This Answer Correct ? | 2 Yes | 8 No |
Answer / erick atienza
Since the connection is in series, it will increase because the the current will increase.
Is This Answer Correct ? | 5 Yes | 12 No |
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