Electric Charges and Fields — Physics STD 12 Science — Question

As the switch S is closed in the circuit shown in figure, current passed through it is

(a) 4.5 A

(b) 6.0 A

(c) 3.0 A

(d) Zero

An ammeter with internal resistance 90 Ω reads 1.85 A when connected in a circuit containing a battery and two resistors 700 Ω and  410 Ω  in series. Actual current will be

(a) 1.85 A	(b) Greater than 1.85 A
(c) Less than 1.85 A	(d) None of these

When hydrogen atom is in its first excited level, its radius is .... its ground state radius

(a) Half

(b) Same

(c) Twice

(d) Four times

the anode is kept at positive potential with respect to the cathode:

 In this reaction how many α  and β  particles are emitted

(a) 6α,3β

(b) 3 α, 4β

(c) 4 α, 3β

(d) 3α, 6β

The shortest wavelength of X-rays emitted from an X-ray tube depends on the

(a) Current in the tube	(b) Voltage applied to the tube
(c) Nature of gas in the tube	(d) Atomic number of target material

A 2 MeV proton is moving perpendicular to a uniform magnetic field of 2.5 tesla. The force on the proton is

(a) 2.5

(b) 7.6

(c) 2.5

(d) 7.6

Two free parallel wires carrying currents in the opposite directions:

The kinetic energy of the electron in an orbit of radius r in hydrogen atom is (e = electronic charge)

(a)

(b)

(c)

(d)

In a certain arrangement, a proton does not get deflected while moving through a magnetic field region. Under what condition is it possible?