Friday, September 8, 2017

PHYSICS XII TO BE SUBMITTED ON BHADRA 27.

1.      Two bulbs of 60 W and 100 W are connected in series and this combination is connected across the mains. Which bulb will glow more brightly? Give reason.
2.      You are given n wires each of resistance rΩ. What is the ratio of maximum to minimum resistance that can be obtained from these wires?
3.      Is terminal p.d. always connected in parallel with the load resistance?
4.      Two bulbs have the filament of the same length. If one is of 40 watt and the other 60 watt, which one has thicker filament if they are joined in series?
5.      Two bulbs have the filament of the same length. If one is of 40 watt and the other 60 watt, which one has thicker filament if they are joined in parallel?
6.  Why are alloys constantan and manganin used to make standard resistors?
7.  A large number of free electrons are present in metals. Why is there no current in the absence of electric field across it?

8.  Explain the significance of a shut with a diagram.
9. Discuss focault's experiment to find velocity of light.
10. Derive decay equation.
11. State and prove Joules law of heating.
12. A cell of emf 12V and negligible internal resistance is joined in series with resistance of 500Ω and 2000Ω. A voltmeter of internal resistance 1000Ω is placed across (a) 500Ω resistor (b) 2000Ω resistor. Find the voltmeter reading in each case.
13. An electron beam passes through a parallel plate capacitor with a velocity of 107m–1. The length of each plate is 10cm while the distance between the plates is 5cm. If the electric intensity between the plates is 20Vcm–1, find the acceleration and the angle of deflection of the beam. (Given e = 1.6 x 10–19 C and mass of electron 9.1 x 10–31 kg) 

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