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Asked: March 28, 2025In: Class 12 Physics

Two concentric and coplanar circular loops P and Q have their radii in the ratio 2 : 3. Loop Q carries a current 9 A in the anticlock wise direction. For the magnetic field to be zero at the common centre, loop P must carry

The correct answer is (D) 6 A in the clockwise direction. To nullify the magnetic field at the common center, the magnetic fields produced by both loops must be equal and opposite. Using the ratio of radii and currents, loop ...

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Sanjay01 Kumar

Asked: March 25, 2025In: Class 12 Physics

How many lamps each of 50 W and 100 V can be connected in parallel across a 120 V battery of internal resistance 10 Q, so that each glows to full Power?

The resistance of each lamp is R = V/P = 100/50 = 200Ω. Let n be the number of lamps. The total resistance in parallel is: 1/Req = n/200 Including battery resistance: Rtotal = 200/n + 10 For full power:

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Sanjay01 Kumar

Asked: March 25, 2025In: Class 12 Physics

The supply voltage to room is 120 V. The resistance of the lead wires is 6 Ω. A 60 W bulb is already switched on. What is the decrease of voltage across the bulb, when a 240 W heater is switched on in parallel to the bulb?

Given: Supply voltage = 120V, Lead wire resistance = 6Ω, Bulb power = 60W, Heater power = 240W. using R = V²/P, Bulb resistance = 240, Heater resistance = 60Ω. Current before: 0.5A, Current after: 2.5A. Voltage drop increase: 12V.