Sample Paper Bihar Board Class XII Physics

(Set-1)

1. S. I. unit of flux is
(A) Ohm
(B) Weber
(C) Tesla
(D) None
2.The relation between geometric length (L _g) and magnetic length ( L_m) is–
(A) L_m=5/6L _g
(B) L_m=6/5L _g
(C) L_m=L _g
(D) L_m=2L _g

3.Reflactic index of glasses and water are3/2 and 4/ 3 respectively for say of light going to water for glan, the critical only will be
(A) sin-1 8/9
(B) sin-1 9/8
(C) sin-1 3/4
(D) sin-1 2/3

4. The modulation Index in amplitude modulation is–
(A) Always zero
(B) Between 0 & 1
(C) Between 1 & ∞
(D) None of these
5.Air bulbla inside water shines due to?
(A) Reflection
(B) Reflution
(C) T.I.R.
(D) None of these
6. When a dielectric in introduced into the gap of a parallel plate capacitor, the capacitance of the capacitor :
(A) Decreases
(B) Increases
(C) Remains same
(D) None of these

Sample Paper Bihar Board Class XII Physics

(Set-2)

1. Kirchhoff's loop rule is a consequence of
(A) Non conservative nature of electric field
(B) Conservative nature of electric field
(C) Conservative nature of magnetic field
(D) Non conservative nature of magnetic field

2. The magnetic field at the centre of a current carrying circular loop is B. If the radius of the loop is doubled
keeping the current unchanged, the magnetic field at the centre of the loop will become.
(A) B/4
(B) B/2
(C) 2 B
(D) 4 B

3. Change on one proton in coulomb is
(A) 1.6 × 10–¹⁹C
(B) 9.1 × 10–³¹C
(C) –1.6 × 10–¹⁹C
(D) None of these

4. A cell of emf 1.5 v is connected directly to an ammeter of resistance 0.05 Ω . If the current in the circuit is 2.0A, the internal resistance of the cell is:
(A) 0.7 Ω
(B) 0.8 Ω
(C) 0.9 Ω
(D) 1.0 Ω

5. In young's double slit experiment the distance between the slits and the screen is doubled and the separation between the the slits is reduced to half. The fringe width.
(A) is doubled
(B) becomes four times
(C) is halved
(D) remains unchanged

Sample Paper Bihar Board Class XII Physics

(Set-3)

1.Light year is the unit of–
(A) Distance
(B) Time
(C) Energy
(D) Intensity of light

2.When a ray of light (white) enters a lens, it under goes a change in
(A) Wavelength only
(B) Velocity only
(C) frequency only
(D) both velocity and wavelength

3.Which one of the following is the unit of electricfield a intensity
(A) Coulomb
(B) Newton
(C) Volt
(D) N-C

4.Fg and Fe represent the gravitational and electrostagific forces respectively between two electrons situated at some distance, the ratio of Fg /Fe is of the order of
(A) 9.8
(B) 109
(C) 1042
(D) 10–42

5.When light travels from one medium to an other, which of the following does not change–
(A) Frequency
(B) refractive
(C) velocity
(D) wavelength

6.Capacity of an isolated sphere is increased n times when it is enclosed by an earthed concentric sphere. The ratio of their radii is :)
(A) n²/n-1
(B) n/n-1
(C) 2n/n+1
(D) 2n+1/n+1

Sample Paper Bihar Board Class XII Physics

(Set-4)

1.Fusion taken place at high temperature because:
(A) atoms are ionized at high temperature
(B) molecules break u p at high temperature
(C) nuclei break up at high temperature
(D) kinetic energy is high enough too overcome repulsion between nuclei.

2. If an electric dipole is kept in a uniform electric field then resultant electric force on it, is
(A) always zero
(B) never zero
(C) depends upon capacity of dipole
(D) one

3. In L–C–R circuit to produce resonance—
(A) ωc=1/ωC
(B) ωc=1/ωC
(C) ω=ωC
(D) None

4. A conducting rod is rotated in uniform magnetic force field (B) with constant velocity (V). The p.d. is developed between ends of rod when—
(A) V II l
(B) V II B
(C) l II B
(D) None

5. In binary system 111 represents—
(A) 1
(B) 3
(C) 7
(D) 100

6. Which of the following help us for recognition of precious stone ?
(A) Ultraviolet rays
(B) Infrared
(C) x-rays
(D) none

Sample Paper Bihar Board Class XII Physics

(Set-5)

1. In binary system 111 represents–
(A) 1
(B) 3
(C) 7
(D) 100

2. In semiconductors which are responsible for conduction–
(A) electron & holes both
(C) only holes
(D) none

3.In binary system 111 represents–
(A) 1
(B) 3
(C) 7
(D) 100

4.By emission of which of the following element remains unchanged.
(A) α -decay
(B) β -decay
(C) β – decay
(D) γ -decay

5.The number of electrons taken out from a body to produce 1 coulomb of change with to–
(A) 6.25 × 1018
(B) 6.25 × 108
(C) 6.23 × 1023
(D) None

6.Two lens of power –15D and +5D are placed is contact co-axially. The focal length of equivalent lens is–
(A) –10 cm
(B) –20 cm
(C) +10 cm
(D) none

7.The work done in rotating an electric dipole in an electric field is–
(A) W = ME (1 – cosθ)
(B) W = ME tanθ
(C) W = ME secθ
(D) None

8.If sphere of bad conductor is given charge then it is distributed on–
(A) surface
(B) Inside the surface also
(C) only inside the surface
(D) None

9.Which of the following has higher magnetic susceptibility ?
(A) diamagnetic
(B) paramagnetic
(C) ferromagnetic
(D) None