Model Paper 3 — Physics STD 12 Science — Question

The area of a coil is 500cm² and the number of turns in it is 2000. It is kept perpendicular to a magnetic field of induction 4 × 10-5Wb/ m². The coil is rotated through 180 in 0.1 second. If the resistance of the total circuit is 20Ω, then the value of the induced charge flowing in the circuit will be :

What is the atomic mass (u) of calcium?

The rest energy of an electron is 0.511 MeV. The electron is accelerated from rest to a velocity 0.5 c. The change in its energy will be

(a) 0.026 MeV

(b) 0.051 MeV

(c) 0.079 MeV

(d) 0.105 MeV

The total charge of the isolated system is always:

Taking Rydberg’s constant  first and second wavelength of Balmer series in hydrogen spectrum is

(a) 2000 Å, 3000 Å

(b) 1575 Å, 2960 Å

(c) 6529 Å, 4280 Å

(d) 6552 Å, 4863 Å

Which of the following is wrong for interference fringes?

Two metallic charged spheres whose radii are 20 cm  and 10 cm respectively, have each 150 micro - coulomb  positive charge. The common potential after they are connected by a conducting wire is

(a) 9 ×

(b) 4.5 ×

(c) 1.8 ×

(d) 13.5 ×

A concave mirror of focal length f, has formed the image of magnification m, the distance of the object from the mirror is :

Samples of two radioactive nuclides A and B are taken. λA and λB are the disintegration constants of A and B respectively. In which of the following cases, the two samples can simultaneously have the same decay rate at any time?