OCR Physics Past Paper PDF

Question Q(r  R ) based on Application of Gauss Law (C) (D)none of these 4  0 ( R 2  r 2 )...

Question Q(r  R ) based on Application of Gauss Law (C) (D)none of these 4  0 ( R 2  r 2 ) Q.96 Three charges q1 = 1µC, q2 = 2 µC and Q.102 The electric field inside a spherical shell q3 = –3 µC and four surfaces S1, S2, S3 of uniform surface charge density is - and S4 are shown. The flux emerging (A) Zero through surface S2 in N-m2 / C is - (B) Constant, different from zero (C) Proportional to the distance from the S3 centre q1 q3 q2 (D) None of the above S1 S2 S4 Q.103 The earth has a net charge equivalent to 1 electron/m2 on the surface area of (A) 36 × 103 (B) –36 × 103 radius (C) 36 × 109 (D) –36 × 109 6.4 × 106 m. Its potential would be- (A) + 0.12 volt (B) – 0.12 volt Q.97 A surface enclosed an electric dipole, the flux through the surface is- (C) + 1.2 volt (D) – 1.2 volt (A) Infinite (B) Positiv (C) Negative (D) Zero Q.104 The electric potential at the surface of an atomic nucleus (Z = 50) of radius 9 × 10– Q.98 Total flux coming out of some closed 15 m is - surface in vacuum which encloses a point charge 8.85 µC is- (A) 80V (B) 8 × 106 (A) 106 V-m (B) 2 × 106 (C) 8 × 104 V (D) 8 × 102 V (C) 1012 V-m (D) 2 × 1012 Vm Q.105 A cubical box of side 1m is immersed a Q.99 A square of side 20 cm is enclosed by a uniform electric field of strength 104 surface of sphere of radius 80 cm. N/C. The flux through the cube is- Square and sphere have the same centre. (A) 104 (B) 6 × 104 Four charges +2 × 10–6 C, –5 × 10–6 C, – (C) 2 × 104 (D) Zero 3 × 10–6 C, +6 × 10–6C are located at the four corners of a square, Then out going total flux from spherical surface in Q.106 A charge (q) is located at one corner of a N-m2/C will be- cube. The total electric flux through the (A) zero (B) (16) × 10–6 cube is- q q q q (C) (8) × 10–6 (D) (36 ) × 10–6 (A) (B) (C) o 24 o 6 o 8 o Q.100 The flux emerging out from any one face of the cube when a point charge q is Q.107 A large isolated metal sphere of radius placed at its centre - (R) carries a fixed charge. A small q q q q charge is placed at a distance (r) from its (A) (B) (C) (D) surface experiences a force which is - 6 0 3 0 0 4 0 (A) Proportional to R Q.101 A charge Q is distributed over two (B) Independent of R and concentric hollow spheres of radii r and (C) Inversely proportional to (R+r) R (> r) such that their surface charge (D) inversely proportional to r2 densities are equal. Find the potential at the common centre- Q.108 A hollow sphere of charge does not Q (r  R ) Q(R 2  r ) 2 produce an electric field at any- (A)  (B) 4 0 ( R  r ) 2 4  0 ( r  R ) (A) Interior point (B) Outer point  (C) Surface point V (D) None of the above (D) Q.109 A spherical conductor of radius 50 cm r has a surface charge density of 8.85 × 10–6 C/m2. The electric field near the surface in N/C is- Question based on Electric dipole (A) 8.85 × 10–6 (B) 8.85 × 106 (C) 1 × 106 (D) Zero Q.111 A solid conducting sphere having a charge Q is surrounded by an uncharged Q.114 If an electric dipole is kept in a uniform concentric conducting hollow spherical electric field. Then it will experienc shell. Let the potential difference between the surface of the solid sphere (A) a force and that of the outer surface of the (B) a couple and moves hollow shell be V. If the shell is now (C) a couple and rotates given a charge of 3Q, the new potential (D) a force and moves. difference between the same two surfaces is Q.115 An electric dipole consists of two (A) V (B) 2V opposite charges each of magnitude 1 × (C) 4V (D) –2V 10–6 C separated by a distance 2 cm. The dipole is placed in an external field of Q.112 The electric field intensity at a point 10 × 105N/C. The maximum torque on located at distance r (r < R) from the the dipole is - center of a spherical conductor (radius (A) 0.2 × 10–3 N-m (B) 1.0 × 10–3 N- R) charged Q will be – m (A) kQR/r3 (B) kQr/R3 (C) 2 × 10–2 N-m (D) 4 × 10–3 N- 2 (C) kQ/r (D) zero. m Q.113 The dependence of electric potential V Q.116 The ratio of the electric field due to an on the distance 'r' from the centre of a electric dipole on its axis and on the charged spherical shell is shown by. perpendicular bisector of the dipole is- (A) 1 : 2 (B) 2 : 1 V (C) 1 : 4 (D) 4 : 1 Q.117 The region surrounding a stationary (A) electric dipole has- r (A) electric field only V (B) magnetic field only (C) both electric and magnetic fiel (B) (D) neither electric nor magnetic field r Q.118 The electric potential at distance r due to V an electric dipole of moment p will be- (C) p. r p. r (A) k 3 (B) k r r r2 k( p  r ) k( p  r ) (C) (D) r r2