1
CBSE 12th Physics Delhi Set 1 - 2023
Subjective
+3
-0

(a) A plane wave-front propagating in a medium of refractive index '$$\mu_1$$' is incident on a plane surface making an angle of incidence (i). It enters into a medium of refractive index $$\mu_2\left(\mu_2>\mu_1\right)$$. Use Huygen's construction of secondary wavelets to trace the retracted wave-front. Hence, verify Snell's law of refraction.

OR

Using Huygen's construction, show how a plane wave is reflected from a surface. Hence, verify the law of reflection.

2
CBSE 12th Physics Delhi Set 1 - 2023
Subjective
+3
-0

An alternating voltage of $$220 \mathrm{~V}$$ is applied across a device $$X$$. A current of 0.22 A flows in the circuit and it lags behind the applied voltage in phase by $$\pi / 2$$ radian. When the same voltage is applied across another device $$Y$$, the current in the circuit remains the same and it is in phase with the applied voltage.

(i) Name the devices $$X$$ and $$Y$$ and,

(ii) Calculate the current flowing in the circuit when the same voltage is applied across the series combination of $$\mathrm{X}$$ and $$\mathrm{Y}$$.

3
CBSE 12th Physics Delhi Set 1 - 2023
Subjective
+3
-0

State the basic principle behind the working of an ac generator. Briefly describe its working and obtain the expression for the instantaneous value of emf induced.

4
CBSE 12th Physics Delhi Set 1 - 2023
Subjective
+3
-0

(a) Briefly describe how the current sensitivity of a moving coil galvanometer can be increased.

(b) A galvanometer shows full scale deflection for current $$I_g$$. A resistance $$R_1$$ is required to convert it into a voltmeter of range $$(0-V)$$ and a resistance $$R_2$$ to convert it into a voltmeter of range $$(0-2 \mathrm{~V})$$. Find the resistance of the galvanometer.

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