Advertisements
Advertisements
प्रश्न
Two bulbs are rated: bulb A 100W, 120 V bulb B 10W, 120 V. If both are connected across a 120V supply, which bulb will consume more energy, When in series? Also calculate the current through each bulb in above cases.
Advertisements
उत्तर
In the case of bulb A, Power: P = `"V"^2/"R"_"A"`
RA = `"V"^2/"P" = (120 xx 120)/100` = 144 Ω
i.e., Resistance (RA) of bulb, A = 144 Ω
Similarly resistance RB of bulb, B = `"V"^2/"P"`
`= (120 xx 120)/10 = 1440` Ω
When the bulb are connected in series:
R = RA + RB = 144 + 1440 = 1584 Ω
∴ Current in the circuit `= "V"/"R" = 120/1584 = 0.076` A
Being in series, the same current passes through both the bulbs.
Power consumed in bulbs A = PA = i2 RA = (0.076)2 × 144 = 0.8317 W
Power consumed in bulbs B = PB = i2 RB = (0.076)2 × 144 = 8.317 W
This clearly shows that PA < PB i.e., bulb B (10W, 120 V) consumes more energy when these are connected series.
APPEARS IN
संबंधित प्रश्न
An electric lamp is labelled 12 V, 36 W. This indicates that it should be used with a 1 V supply. What other information does the label provide?
Define watt. Write down an equation linking watts, volts and amperes.
Name the S.I. unit of electrical energy. How is it related to Wh?
A current passes through a resistor. Let K1 and K2 represent the average kinetic energy of the conduction electrons and the metal ions, respectively.
A coil of copper wire is connected to a galvanometer. What would happen if a bar magnet is:
(i) Pushed into the coil with its north pole entering first?
(ii) Held at rest inside the coil?
(iii) Pulled out again?
Household wiring for lamp connections can either be done in parallel or in series.Which one would you prefer? Give a reason for your answer.
I ampere of current is passed through a resistor of resistance R ohm for time t second. Obtain expression for
(i) the electrical energy, and
(ii) the electrical power spent.
Two bulbs are rated: bulb A 100W, 120 V bulb B 10 W, 120 V. If both are connected across a 120V supply, which bulb will consume more energy, When in parallel? Also calculate the current through each bulb in the above cases.
