Consider  a particle  on which  constant forces $F_{1}=\hat{i}+2\hat{j}+3\hat{k}$ N and $F_{2}=4\hat{i}-5\hat{j}-2\hat{k}$ N act together resulting in a displacement from position  $r_{1}=20\hat{i}+15\hat{j}$ cm to $r_{2}=7\hat{k}$  cm. The  total work done on the particle is 

A) -0.48 J

B) +0.48J

C) -4.8 J

D) +4.8J


A current-carrying wire in its neighbourhood produces

A) electric field

B) electric and magnetic fields

C) magnetic field

D) no field


The declaration of a car travelling on a straight highway is a function of its instantaneous velocity v given by $\omega=a\sqrt{v}$, where a is a constant. If the initial velocity of the car is 60 km/h, the distance of the car will travel and the time it takes before it stops  are 

A) $\frac{2}{3}m,\frac{1}{2}s$

B) $\frac{3}{2a}m,\frac{1}{2a}s$

C) $\frac{3a}{2}m,\frac{a}{2}s$

D) $\frac{2}{3a}m,\frac{2}{a}s$


Which of the following statement is not true?

A) the resistance of an intrinsic semicondutor decrease with increase in temperature

B) doping pure Si with trivalent impurities gives n-type semiconductor

C) the majority carriers is n-type semiconductors are holes

D) a p-n junction can act as a semiconductor diode


 A sound  wave of freequency v Hz  initially travels a distance of 1 km in air . Then , it gets reflected into a water reservoir  of depth 600 m. The frequency of the wave at the bottom of the reservoir is

 $(V_{air}=340 m/s, V_{water}=1484 m/s)$ 

A) > v Hz

B) < v Hz

C) v Hz

D) 0(the sound wave gets attenuated by water completely)