Current Electricity Charging Discharging Of Capacitors Question 492
Question: Two bulbs of 500 watt and 200 watt are manufactured to operate on 220 volt line. The ratio of heat produced in 500 W and 200 W, in two cases, when firstly they are joined in parallel and secondly in series, will be
[MP PET 1996; DPMT 1999]
Options:
A) $ \frac{5}{2},,\frac{2}{5} $
B) $ \frac{5}{2},,\frac{5}{2} $
C) $ \frac{2}{5},,\frac{5}{2} $
D) $ \frac{2}{5},,\frac{2}{5} $
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Answer:
Correct Answer: A
Solution:
Resistance $ R _{1} $ of 500 W bulb $ =\frac{{{(220)}^{2}}}{500} $ Resistance $ R _{2} $ of 200 W bulb $ =\frac{{{(220)}^{2}}}{200} $ When joined in parallel, the potential difference across both the bulbs will be same. Ratio of heat produced $ =\frac{V^{2}/R _{1}}{V^{2}/R _{2}}=\frac{R _{2}}{R _{1}}=\frac{5}{2} $ When joined in series, the same current will flow through both the bulbs. Ratio of heat produced $ =\frac{i^{2}R _{1}}{i^{2}R _{2}}=\frac{R _{1}}{R _{2}}=\frac{2}{5} $
BETA
