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1.

In the hydrogen emission spectrum, for any series, the principal quantum number is n. Corresponding maximum wavelength  $\lambda$  is (R= Rydberg's constant )

A) $\frac{R(2n+1)}{n^{2}(n+1)}$

B) $\frac{n^{2}(n+1)^{2}}{R(2n+1)}$

C) $\frac{n^{2}(n+1)^{}}{R(2n+1)}$

D) $\frac{R(2n+1)}{n^{2}(n+1)^{2}}$

2.

A hole is drilled halfway to the centre of the earth. A body weighs 300N on the surface of the earth. How much will, it weigh at the bottom of the hole?

A) 200 N

B) 250 N

C) 120 N

D) 150 N

3.

The damped SHM , the SI unit of damping constant is

A) $\frac{N}{s}$

B) $\frac{kg}{s}$

C) $\frac{kg}{m}$

D) $\frac{N}{m}$

4.

The vectors (A+B) and (A-B)  are at right angles to each other. This is possible under the condition

A) |A|=|B|

B) A.B=0

C) A.B=1

D) A x B=0

5.

A rod l m long is acted upon by couples as shown in the figure. The moment of the couple is $\tau$ Nm. If the force at each end of the rod, then the magnitude of each force is

$(\sin 30^{0}=\cos 60^{0}=0.5)$

A) $\frac{\tau}{l}$

B) $\frac{l}{2 \tau}$

C) $\frac{2 \tau}{l}$

D) $\frac{2 l}{ \tau}$

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