VITEEE 2017 :: Physics :: General questions

• Physics - General questions

The power dissipated in the circuit shown in the figure is 30 Watts. The value of R is

Answer:

Explanation:

The power dissipated in the circuit

$P = \frac{V^{2}}{R_{eq}}$   ....(1)

v = 10 volt

$\frac{1}{R_{eq}} = \frac{1}{R}+\frac{1}{5}$ = $\frac{5+R}{5R}$

$R_{eq}$ = $\frac{5R}{5+R}$

P = 30W

Substituting the values in equation (1)

$30 = \frac{10^{2}}{\frac{5R}{5+R}}$ 

$\frac{15R}{5+R}$ = 10 → 15R = 50 + 10R

5R=50 → R = 10Ω

A potentiometer wire, 10 m long, has a resistance of 40Ω. It is connected in series with a resistance box and a 2 V storage cell. If the potential gradient along the wire 0.1 m is V/cm, the resistance unplugged in the box is

Answer:

Explanation:

Potential gradient along wire = $\frac{Potential difference along wire}{length of wire}$

or, 0.1×10^-3 = $\frac{I\times40}{1000}$V/cm

or, Current in wire, I = $\frac{1}{400}$ A

or, $\frac{2}{40+R}$ = $\frac{1}{400}$ or R = 800 - 40=760 Ω

Transfer characteristics [output voltage (V₀) vs input voltage (V_i) ] for a base biased transistor in CE configuration is as shown in the figure. For using transistor as a switch, it is used

Answer:

Explanation:

I →ON

II → OFF

In II^nd state it is used as a amplifier it is active region

A prism has a refracting angle of 60°. When placed in the position of minimum deviation, it produces a deviation of 30°. The angle of incidence is 

Answer:

Explanation:

$i = \frac{A+\delta_{m}}{2}$ = $\frac{60+30}{2}$ = 45°

Resonance frequency of LCR series a.c. circuit is f₀. Now the capacitance is made 4 times, then the new resonance frequency will become

Answer:

Explanation:

In LCR series circuit, resonance frequency f₀ is given by

$L\omega = \frac{1}{C\omega}\Rightarrow \omega^{2} =\frac{1}{LC}$

$\therefore\omega = \sqrt{\frac{1}{LC}}=2\pi f_{0}$

$\therefore f_{0} = \frac{1}{2\pi\sqrt{LC}}$ or $f_{0} \propto \frac{1}{\sqrt{C}}$

When the capacitance of the circuit is made 4 times, its resonant frequency become f'₀

$\frac{f'_{0}}{f_{0}}=\frac{\sqrt{C}}{\sqrt{4C}}$

OR $f'_{0} = \frac{f_{0}}{2}$

• Physics - General questions