Physics Self-Test - Page 2
4- Direction of λa and a is same if λ is _________
- a) imaginary
- b) negative
- c) positive
- d) zero
5- If a = i^ + j^ + k^ and λ=5, what is value of λa?
- a) i^ + j^ + k^
- b) 5i^ + 5j^ + 5k^
- c) i^ + 5j^ + 5k^
- d) 10i^ + 10j^ + 10k^
6- Find values of x, y, z if vectors a = xi^ + 2j^ + zk^ and b = 2i^ + yj^ + k^ are equal.
- a) x=2, y=2, z=1
- b) x=1, y=2, z=1
- c) x=2, y=1, z=1
- d) x=2, y=2, z=2
Extra: If a = i^ + 2j^ and b = 2i^ + j^ , Is |a| = |b|?
Explanation: Both vectors have the same magnitude: √(1² + 2²) = √5.
7- According to coulomb's law, the electric force is proportional ...... to r² and ........ to the interaction charges.
- (a) Directly-Inversely
- (b) Inversely-Directly
- (c) Directly- Directly
- (d) no relation
8- Coulomb's law is only valid in the case of ......... charge.
- (a) movable
- (b) accelerated
- (c) Static
- (d) All of the above
9- When the number of electric field lines increase, the flux will be
- (a) Increase
- (b) Decrease
- (c) Constant
- (d) None of the above
10- F21 means that a force ....... is affected by the electric field of another force.
- (a) F - F2
- (b) F2 - F1
- (c) F1 - F2
- (d) None of the above
11- Is the space around the charge when the charge's effect appears
- (a) Electrical force
- (b) Electrical potential
- (c) Electrical field intensity
- (d) Electrical field
12- A 10 mC particle is moved from infinity to a point where the electric potential energy is 5 J. What is the electric potential at the particle's destination?
- (a) 500 V
- (b) 50 V
- (c) 5 V
- (d) 0.5 V
Explanation: V = U / q = 5 J / (10 × 10»³ C) = 500 V.
13- The unit of potential (V) =......
- (a) N/C
- (b) C/F
- (c) J/C
- (d) Both b & c
14- Two charges 1C and -4C exists in air. What is the direction of force?
- (a) Away from 1C
- (b) Away from -4C
- (c) From 1C to -4C
- (d) From -4C to 1C
Explanation: Since they are opposite charges, they attract each other. The force on the 1C charge points toward the -4C charge, and the force on the -4C charge points toward the 1C charge (from -4C to 1C).
15- The electric lines of force about a point positive charge are
- (a) Circular, anticlockwise
- (b) Circular, clockwise
- (c) radial, inward
- (d) radial, outward
16- Two charged spheres of radii 10 cm and 15 cm are connected by a thin wire. No current will flow if they have
- (a) The same potential
- (b) The same charge
- (c) The same energy
- (d) The same field on their surface