# +2 Physics - Random One Mark Collection - Set 10

The last set of question in this random collection of questions for Plus 2 physics examination. Questions from 81-90 are provided below:-

81) Torque on a dipole in a uniform electric field is maximum when angle between P and E is

a) 90
b) 45
c) 180
d) 0

82) The radio-Isotope used in agriculture is

a) 15P32
b) 11Na23
c) 27Co60
d) 11Na24

83) In an AM superheterodyne receiver, the local oscilllator frequency is 1·245 MHz.The tuned station frequency is

a) 455 kHz
b) 690 kHz
c) 790 kHz
d) 990 kHz

84) If the radius of third Bohr orbit in hydrogen atom is r, then the de Broglie wavelength of electron In this orbit is

a) r/3
b) 2*pi*r/3
c) 3r
d) 6*pi*r

85) In LCR series a.c. circuit. the phase difference between current and voltage is 30 degree.The reactance of the circuit Is 17·32 ohm . The value of resistance Is

a) 30 ohm
b) 10 ohm
c) 17.32 ohm
d) 1.732 ohm

86) The energy of the electron in the first orbit of hydrogen atom is - 13·6 eV. Its potential energy is

a) 13·6 eV
b) - 13·6 eV
c) - 27·2 eV
d) 27·2 eV

87) A Coolidge tube operates at 18600 V. The maximum frequency of X-radiation emitted from it

a) 4·5 x 1018 Hz
b) 45x1018 Hz
c) 4·05 x 1018 Hz
d) 45.5 x 1018 Hz

88) The work done In moving 4 micro Coulomb charge from one point to another in an electric field is 0·012 J. The potential difference between them is

a) 6000 V
b) 3000 V
c) 48 x 103 V
d) 30 V

89) The unit of electric flux is

a) Nm2C-1
b) Nm-2C-1
c) Nm2C
d) Nm-2C

90) Which of the following principles Is used in a thermopile?

a) Peltier effect
b) Scebeclt effect
c) Joule's effect
d) Thomson effect