physics question mcq

Q.1 If the number of turns of a solenoid circular coil is doubled, but the current in the coil and radius of the coil remains same, then what will be the magnetic flux density produced by the coil?
A) Magnetic flux density will be halved
B) Magnetic flux density increases by different amount at different points
C) Magnetic flux density remains unchanged
D) Magnetic flux density will be doubled

Q.4 A 10 cm long solenoid has 100 turns. What will be the magnetic field inside it along its axis if one micro ampere current is passed through it?
A) 4π x 10-13 tesla                                  C) 4π x 10-10 tesla
B) 4π x 10-7 tesla                                    D) 4π x 10-16 tesla

Q.7 A solenoid is cut into two halves. Magnetic induction due to same current in each half will be:
A) Half of the original                             C) Same as original

B) Double of the original                    D) Four times of the original

Q.8      A long straight current carrying conductor has current directed from bottom to top when held vertically. What will be the direction of magnetic field lines when observed from below the conductor?     
A) Clockwise                                                      C) Vertically upward
B) Anti clockwise                                               D) Vertically downward

Q.10 A solenoid 15 cm long has 300 turns of wire. A current of 5 A flows through it. What is the
magnitude of magnetic field inside the solenoid?
A) 75 x 10⁷ T                                         C) 4π x 10^-3 T
B) 60 x 10⁺³ T                                       D) 750π x 10⁺³ T

Q.11 Due to current in a straight conductor the difference between magnetic field lines

A) Increases away from conductor     C) Increases towards conductor

B) Decreases away from conductor    D) Decreases and then increases towards conductor