1
CBSE 12th Physics Delhi Set 1 - 2023
MCQ (Single Correct Answer)
+1
-0

Which of the following statements about a series LCR circuit connected to an ac source is correct?

A
If the frequency of the source is increased, the impedance of the circuit first decreases and then increases.
B
If the net reactance $$\left(X_L-X_C\right)$$ of circuit becomes equal to its resistance, then the current leads the voltage by $$45^{\circ}$$.
C
At resonance, the voltage drop across the inductor is more than that across the capacitor.
D
At resonance, the voltage drop across the capacitor is more than that across the inductor.
2
CBSE 12th Physics Delhi Set 1 - 2023
MCQ (Single Correct Answer)
+1
-0

According to Huygens principle, the amplitude of secondary wavelets is

A
equal in both the forward and the backward directions.
B
maximum in the forward direction and zero in the backward direction.
C
large in the forward direction and small in the backward direction.
D
small in the forward direction and large in the backward direction.
3
CBSE 12th Physics Delhi Set 1 - 2023
MCQ (Single Correct Answer)
+1
-0

The radius of the $$\mathrm{n}^{\text {th }}$$ orbit in Bohr model of hydrogen atom is proportional

A
$$n^2$$
B
$$\frac{1}{n^2}$$
C
$$n$$
D
$$\frac{1}{n}$$
4
CBSE 12th Physics Delhi Set 1 - 2023
MCQ (Single Correct Answer)
+1
-0

Assertion (A) : The resistance of an intrinsic semiconductor decreases with increase in its temperature.

Reason (R) : The number of conduction electrons as well as hole increase in an intrinsic semiconductor with rise in its temperature.

A
Both Assertion (A) and Reason (R) are true and (R) is the correct explanation of (A).
B
Both Assertion (A) and Reason (R) are true and (R) is NOT the correct explanation of (A).
C
Assertion (A) is true and Reason (R) is false.
D
Assertion (A) is false and Reason (R) is also false.
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