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1-In a X- ray production device operation potential is 25 kv. Thecurrent between the cathode and anode is 2 mA. One percent of thekinetic energy of the electrons striking the target , is converted in toX-rays. The power obtained as X-rays is

(a) 50 watt (b) 45 watt (c) 5 watt (d) 0.5 watt

2- The wavelength of the K X-ray are 1 and 2 for target metals

with atomic numbers 26 and 31 respectively. The ratio 2 / 1 =

(a) 5/6 (b) 25 / 36 (c) 31/ 26 (d) 312/ 262

3- The wavelengths of the K , K and L X-ray are 1 , 2 and 3respectively with same target metal. The correct relation is

(a) 1 > 2 > 3 (b) 2 < 1< 3(c) 1 > 3 > 2 (d) 3 < 1< 2

4- In a X- ray production device, if the operating potential ischanged so as to reduce the shortest wavelength of the x-rayproduced to half of initial velocity. The de Broglie wavelength of the

electrons moving from cathode to anode becomes k times of initialvalue where k =

(a) 2 (b) 1/2 (c) 2 (d) 1

5- Ionization potential for hydrogen atom is 13.6 V. The radius of theelectron orbit in ground state of hydrogen atom is r0. The value ofthe expression e2 / ( 4 0 r0 ) is equal to

(a) 13.6 eV (b) 27.2 eV(c) 6.8 eV (d) none of these

6- The line connecting the electron of hydrogen atom to the

nucleus, sweeps area A in time t when the atom is inground state. How much area is swept by the line connectingthe electron to the nucleus , in a singly ionized helium atom infirst excited state, in time t ?

(a) A (b) 2 A (c) A/ 2 (d) 4 A7- In a hydrogen like atom , when electron has kinetic energy is E1 ,its angular momentum is L1 and when kinetic energy is E2 , its angularmomentum is L2.If E1/E2 equals ( L1/L2 ) x , then x is equal to

(a) 2 (b) -1/2 (c) -1 (d) -2

8- In a region where electric field is uniform and its direction isalong unit vector {3 i - 4 j } / 5 .Then equi potential line passingform point ( 2,1), is given by

(a) 3 x 4 y = 2 (b) 3 x + 4 y = 10(c) 4 x + 3 y = 11 (d) 4 x = 3 y

9- A uniformly charged circular ring is fixed. A charge particle of

mass m is released from center of the ring. The particle reaches atcertain point P on the axis , with speed v0. Now the particle isstopped and then projected to wards the center of ring with velocity2 v0 . The particle will reach at the center of the ring with velocity(a) v0 (b) v02 (c) v03 (d) v0 /2

10- Uniform electric field 50 V / m exist in positive x- direction .Points A and B are situated at x= 2 m and x = 6 mrespectively. If the electric potential at A is 120 volt , then thepotential at B will be ( in volts )(a) 320 (b) -80 (c) 80 (d) none of these

11- In the fig shown the cell has emf E = 1voltand the capacitance is 5 F . Thepoints A and B are at potentials 8 and3 volts respectively. The charge on theleft plate of the capacitor will be(a) 30 C (b) -30 C (c) 20 C (d) -20 C

12- A parallel plate capacitor, with separation d1 between the plates ,is charged up to potential V0.After disconnecting the cell , theseparation between the plates is changed to d2 . Final value of theelectric field in space between the plates will be(a) V0 / d1 (b) V0 / d2 (c) V0 d12 / d2 (d) none

13- In the previous problem work done, in changing the plateseparation against the electrostatic forces , will be proportional to(a) d22 d12 (b) d2 d1 (c)1/d22 1/d12 (d) 1/d2 1/d1

14- A capacitor X of capacitance 1 F withstands a maximumvoltage 6 kV while a capacitor Y of capacitance 2 F withstands themaximum voltage 4 kV . What maximum voltage will the system ofthese capacitors withstand if they are connected in series?(a) 10 kV (b) 9 kV (c) 12 kV (d) 15 kV

15- A galvanometer has coil of resistance 100 ohm and gives fullscale deflection for 30 mA current. If it is to work as a voltmeter of30 volts range, the resistance required to be added will be(a) 1000 ohm (b) 900 ohm (c) 1800 ohm

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16- A capacitor is being discharged through a resistor. In the twosuccessive seconds, heat dissipation through the resistor are H1 andH2 respectively. How much heat will be produced in the resistor inthe next one second?(a) H1 - H2 (b) H2 2/ H1 (c) H1 2/ H2 (d) 2H2 - H1

17- Most temperature sensitive dielectrics are(a) polar dielectric (b) non polar dielectric

(c) all are equally sensitive (d) none

18- A point has position vector which makes angle from thedipole moment vector of a dipole. The distance of the point is rfrom the dipole. The electric potential at the point due to thedipole will be proportional to(a) cos / r (b) cos / r2 (c) sin / r2

19-A positive charge is brought closer to an unchargedconducting body from infinity . The charge is kept at somedistance outside the conductor. Assuming potential zero atinfinity, it can be concluded that the potential(a) at all points inside the conductor is zero

(b) at all points of the conductor is same and negative(c) at all points of the conductor is same and positive

20-An infinitely large slab of thickness 2d is uniformlycharged with volume charge density . One face coincideswith the plane x = d and ther with x = -d . At distance r ( < d) from the y-z plane , electric field will be(a) r/ 0 (b) 0.5 r/ 0 (c) r2/(d 0 )

ANSWERs:ANSWERs :

1-d ; 2-b ; 3-b

4-b ; 5-b ; 6-b

7-d ; 8-a ; 9-c

10-b ; 11-a ; 12-a

13-b ; 14-b

15-b ; 16-b

17-a ; 18-b

19-b ; 20-a