Physics Self-Test - Page 7
41- What will be the total flux passing through the cylinder if the surface A and B have surface area S?
- a) ES
- b) -ES
- c) Zero
- d) ES/ε₀
Explanation: The uniform electric field vectors enter through Cap A (negative flux: $-ES$) and leave through Cap B (positive flux: $+ES$). Since there is no net charge enclosed inside the hollow cylinder volume, the net total flux calculated across the entire surface sums up to exactly zero.
42- A non-conducting sphere has uniform charge density in it. The electric field at a point inside the sphere will be ___________
- a) Zero
- b) Only due to the charge inside that point
- c) Only due to the charge outside that point
- d) Due to the entire charge of the sphere
43- A bar magnet is divided in two pieces. Which of the following statements is true?
- (a) The bar magnet is demagnetized.
- (b) Two new bar magnets are created.
- (c) The magnetic field of each separated piece becomes stronger.
- (d) The magnetic poles are separated.
Explanation: Magnetic monopoles do not exist. Snapping a dipole bar magnet in half automatically generates paired internal north and south boundary faces, forming two standalone functional magnets.
44- A positive charge moves in parallel to a current carrying wire. What is the direction of the magnetic force on the charge?
- (a) To the bottom of the page
- (b) To the top of the page
- (c) Left
- (d) Right
45- If the velocity of the charged particle is perpendicular to the uniform magnetic field, the force will always be directed toward
- (a) Left
- (b) Right
- (c) Out of the center of the circle
- (d) Into the center of the circle
Explanation: The perpendicular magnetic deflection force acts natively as a centripetal force ($F_B = qv \times B$), causing steady circular trajectory lines pulled inward toward a center anchor node.
46- The magnetic force on a stationary charge or a charge moving parallel to the magnetic field is
- (a) Maximum value
- (b) Minimum value
- (c) Zero
- (d) Constant
Explanation: Magnetic force formula is $F = qvB\sin(\theta)$. If the charge is stationary ($v = 0$) or moving parallel ($\theta = 0^\circ \implies \sin(0^\circ) = 0$), the resulting calculation is absolute zero.
47- What is the magnetic field outside a solenoid?
- (a) Infinity
- (b) Zero
- (c) Half the value of the field inside
- (d) Double the value of the field inside
48- How can a magnetic field be produced?
- (a) Using a permanent magnet
- (b) Electric current
- (c) Using a temporary magnet tension
- (d) Using a permanent magnet or electric current
49- As per Michael Faraday, the force is increased if the
- (a) current in the wire is increased
- (b) magnetic field's strength increased
- (c) length of wire increased
- (d) all of the above
50- If a coil carrying current is placed in a uniform magnetic field, then
- (a) emf is produced
- (b) Torque is produced
- (c) Force is produced
- (d) Torque and force is produced