VITEEE 2018 :: Physics :: General questions

• Physics - General questions

A coil of 40 henry inductance is connected in series with a resistance of 8 ohms and the combination is joined to the terminals of a 2 volt battery. The time constant of the circuit is

Answer:

Explanation:

Time constant is L/R

Given, L =  40H & R = 8 Ω

.'. $\tau$ = 40/8 = 5 Sec

The resistance of a wire is 'R' ohm. If it is melted and stretched to 'n' times its original length. its new resistance will be

Answer:

Explanation:

we know that, R = $\frac{\rho l}{A}$

or R = $\frac{\rho l^{2}}{Volume}$ → $R\propto l^{2}$

According to question $l_{2}= nl_{1}$

$\frac{R_{2}}{R_{1}} = \frac{n^{2}l_1^2}{l_1^2}$

or $\frac{R_{2}}{R_{1}} = n^{2}$

$R_{2}= n^{2}R_{1}$

• Physics - General questions