Magnetism — Set 3
Physics · चुंबकत्व · Questions 21–30 of 50
The magnitude of force on a straight conductor of length L carrying current I in a magnetic field B is?
Correct Answer: D. F = BIL sinθ
The correct answer is 'F = BIL sinθ'. The force is given by F equals B I L sine theta for a straight conductor. Theta is the angle between the current direction and the magnetic field. The force is maximum when the conductor is perpendicular to the field.
The torque on a coil with n turns, area A, carrying current I in magnetic field B is commonly written as?
Correct Answer: D. τ = nBIA sinθ
A current-carrying coil in a magnetic field experiences a torque given by nBIA sin theta. This torque tends to rotate the coil. Maximum torque occurs when the coil’s plane is parallel to the field lines.
A moving-coil galvanometer uses a radial magnetic field mainly so that?
Correct Answer: A. Torque is proportional to current for all angles
A radial field keeps the angle between the coil and field effectively constant. This makes the deflecting torque directly proportional to the current. It helps produce a uniform scale in many instruments.
What is the SI unit of magnetic flux (Φ)?
Correct Answer: A. Weber
Magnetic flux is measured in weber in SI units. It represents the total magnetic field passing through a surface. Flux depends on field strength, area, and orientation.
Which relation between tesla and weber is correct?
Correct Answer: B. 1 T = 1 Wb/m^2
Tesla is defined as weber per square meter, so 1 T equals 1 Wb/m^2. This connects flux and area to flux density. A stronger field gives more flux through the same area.
In the CGS system, magnetic flux density is commonly measured in?
Correct Answer: A. Gauss
Gauss is a common CGS unit for magnetic flux density. It is used in many older texts and some applications. A useful conversion is that 1 tesla equals 10,000 gauss.
In the CGS system, magnetic field strength is commonly associated with the unit?
Correct Answer: D. Oersted
Oersted is a common CGS unit linked with magnetic field strength. It appears in older descriptions of magnetic fields. In SI, field strength is commonly expressed in ampere per meter.
Magnetic shielding is commonly done using materials that have?
Correct Answer: A. Very high permeability
Magnetic shielding works best with high-permeability materials that guide field lines. Such materials provide an easier path for magnetic flux. Mu-metal is a well-known shielding material.
The Hall effect refers to the development of a voltage across a conductor when it carries current and is placed in a?
Correct Answer: A. Magnetic field perpendicular to the current
In the Hall effect, moving charges are pushed sideways by a magnetic force. This creates a transverse voltage across the conductor. Hall sensors use this effect to measure magnetic fields.
MRI technology in medicine mainly relies on?
Correct Answer: A. Strong magnetic fields and radio waves
MRI uses very strong magnetic fields along with radio-frequency waves. These fields influence certain atomic nuclei and signals are detected to form images. MRI is valued because it can image soft tissues clearly without using ionizing X-rays.