Most Repeated MDCAT Physics: Magnetism and Electromagnetic Induction MCQs

Explanation

We can determine the direction of the force on the current-carrying wire using Fleming's Left-Hand Rule.Step-by-step explanation:Magnetic field direction (B):It is from the North (N) pole to the South (S) pole (left to right).Current direction (I):The current is going upwards (as shown by the arrow labeled I).Force direction (F):By Fleming's Left-Hand Rule:First finger = Magnetic field (left to right),Second finger = Current (upwards),Thumb = Force (direction of motion).When you align your left hand as per this rule, the thumb points out of the page (towards you).

Explanation

The proton is traveling in the same direction as the solenoid’s axis. Because the magnetic field inside the solenoid is homogenous and parallel to the solenoid, it has no effect on the proton's velocity and it is parallel to the magnetic field( net force on proton is zero) The angle between B and V= 00 According to Lorentz's formula F=q(VxB) or F=qVBsinΘ Here sinΘ =0 this means there will be no force due to the magnetic field at all hence the proton will continue to move with the same velocity along the axis. Since there is no effect on the velocity of the proton so the proton cannot be accelerated along the axis. The proton cannot move in a helical path also.

Explanation

Lenz's law, in electromagnetism, states that an induced electric current flows in a direction such that the current opposes the change that induced it.

Explanation

We know that the force acting on the charge is F = qvBAccording to the formula, it depends on the charge q, its velocity v and the magnetic field in the region B. Hence, option E is correct.

Explanation

The DC current which does not change its intensity is known as steady current. Hence option D is correct.

Explanation

Transformer works on the principal of mutual induction, according to which; "The phenomenon in which a changing current in one coil induces an emf in anofher coil is called the mutual inductance." Hence, option B is correct.

Explanation

Using formula; Np/Ns = Vp/ Vs 500/250 = Vp/Vs 2 = Vp/Vs So Vp = 2Vs or Vs = Vp/2 Hence, secondary voltage or output voltage is half of input or primary voltage. So, option A is correct.

Explanation

Change in magnetic flux per unit area is Φ/A which is equal to B i.e. magnetic flux density. Φ = B . A Hence, option D is correct.

Explanation

Magnetic induction per unit Area is B/A which is equal to Φ i.e., magnetic flux Φ = B . A Hence, option A is correct.

Explanation

Magnetic flux is number of magnetic field lines passing through a surface placed perpendicular to it. Hence, option D is correct.

Explanation

A transformer converts a high voltage low current alternating current to a low voltage high current one and vice versa. Therefore the answer will be B.

Explanation

To calculate the number of turns in the secondary winding, we can use the relationship between the voltage, current, and number of turns in a transformer:Formula:(Vs / Vp) = (Ns / Np)Where: Vs is the voltage in the secondary winding Vp is the voltage in the primary winding Ns is the number of turns in the secondary winding Np is the number of turns in the primary winding We are given: Vs = 300 V Vp = 120 V Np = 400 turns Is = 0.06 A Ip = 2 Substituting the values into the formula: (300 V / 120 V) = (Ns / 400 turns) Simplifying: 2.5 = (Ns / 400 turns) Solving for Ns: Ns = 2.5 * 400 turns = 1000 turnsTherefore, the number of turns in the secondary winding is 1000 turns.

Explanation

The factors on which motional emf depends are the magnetic field and velocity and length of the rod. Thus option D is the correct answer.

Explanation

The time rate of change of magnetic flux has the same dimensions as potential difference, which is measured in volts (V). Therefore, option d is correct.

Explanation

The hydrogen atom, which is effectively a proton in this context since it has lost its electron, is moving east in a magnetic field directed from south to north. To find the direction of the magnetic force acting on the proton, we can use the right-hand rule. For a positive charge like a proton, point your right thumb in the direction of the velocity (east), and your fingers in the direction of the magnetic field (north). The direction in which your palm pushes will indicate the direction of the magnetic force, which is upwards in this case. Therefore, the correct answer is up.Option B (down) is incorrect because the right-hand rule does not support this direction.

Explanation

A moving charged particle is surrounded by three fields:Electric Field: This field arises due to the charge of the particle itself and affects other charges in its vicinity.Magnetic Field: Generated due to the movement of the charge. The interaction between charge and motion creates this field.Gravitational Field: The mass of the particle generates a gravitational field, albeit usually very weak compared to the other two fields.Option A (1 field) is incorrect because it ignores the presence of the magnetic and gravitational fields. Option C (2 fields) is incorrect as it overlooks the gravitational field.

Explanation

Option D) "None of these" is the correct optionPhotons, as electromagnetic waves, do not carry an electric charge, and they are not affected by magnetic fields. Magnetic fields only interact with charged particles, causing them to experience a magnetic force and possibly get deflected.Since photons are uncharged, they do not experience any deflection or interaction with a magnetic field. Therefore, the correct choice is "none of these" because the magnetic field does not affect photons.

Explanation

The unit of magnetic flux is the Weber (Wb).

Explanation

The question states along the axis of a solenoid. This implies that the Magnetic feild is parallel to the direction of current (For magnetic force to act, it is necessary that the direction of current and magentic feild are perpendicular to eachother) Therefore, no force acts and electron moves straight through without getting deflected.

Explanation

r = (m * v) / (q * B) Given:m = 9.109 x 10^-31 kgv = 2.0 x 10^7 m/s q = -1.6 x 10^-19 C B = 1.20 x 10^-3 T Now, let's calculate the radius (r):r = (9.109 x 10^-31 kg * 2.0 x 10^7 m/s) / (1.6 x 10^-19 C * 1.20 x 10^-3 T)r ≈ 9.93 mThe correct option is C. 9.93 m.

Explanation

In Fleming's right hand rule, the fingers of the right hand are used to determine the direction of induced current in a conductor moving through a magnetic field. The thumb indicates the direction of motion, the index finger represents the direction of the magnetic field (from North to South), and the middle finger, which is the second finger, indicates the direction of the induced current in the conductor. Therefore, option B is correct as it accurately reflects the role of the second finger in this rule. Options A, C, and D are incorrect because they misattribute the functions of the fingers to different concepts related to electromagnetism.