A circular coil of radius 5 cm and 50 turns carries a current of 3 ampere. The magnetic dipole moment of the coil is nearly ____.

(a)

1.0 A m²

(b)

1.2 A m²

(c)

0.5 A m²

(d)

0.8 A m²

A thin insulated wire forms a plane spiral of N = 100 tight turns carrying a current I = 8 m A (milli ampere). The radii of inside and outside turns are a = 50 mm and b = 100 mm respectively. The magnetic induction at the centre of the spiral is ______.

(a)

\(5\mu T\)

(b)

\(7\mu T\)

(c)

\(8\mu T\)

(d)

\(10\mu T\)

A wire of length l carrying a current I along the Y direction is kept in a magnetic field is given by \(\vec { B } =\frac { \beta }{ \sqrt { 3 } } =(\hat { i } +\hat { j } +\hat { k } )T.\) The magnitude of Lorentz force acting on the wire is _____.

(a)

\(\sqrt { \frac { 2 }{ { 3 } } } \beta Il\)

(b)

\(\sqrt { \frac { 1 }{ { 3 } } } \beta Il\)

(c)

\(\sqrt { 2 } \beta Il\)

(d)

\(\sqrt { \frac { 1 }{ 2 } } \beta Il\)

The vertical component of Earth’s magnetic field at a place is equal to the horizontal component. What is the value of angle of dip at this place?

(a)

30° 

(b)

45° 

(c)

60° 

(d)

90° 

When current is doubled deflection is also doubled in ______________.

(a)

moving coil galvanometer

(b)

tangent galvanometer

(c)

both of them

(d)

neither of two

An electron of mass 0.90 x 10^-30kg under the action of a magnetic field moves in a circle of 2cm radius at a speed of 3 x 10⁶ m/s if a proton of mass 1.8 x 10^-27 kg was to move in a circle of the same radius in the same magnetic field, then its speed will be _______________.

(a)

3.0 x 10⁶ m/s

(b)

1.5 x 10³ m/s

(c)

6.0 x 10⁴ m/s

(d)

cannot be estimated from the same data

Cyclotron is used to _______________.

(a)

accelerate charged particles or ions to low voltages

(b)

decelerate charged particles or ions to high voltages

(c)

accelerate charged particles or ions to high energies

(d)

accelerate charged particles or ions to high voltages

Joule's law is verified by using _____________.

(a)

Joule's calorimeter

(b)

Joule's voltmeter

(c)

Joule's galvanometer

(d)

thermometer

Thermopile is used to _________________.

(a)

measure temperature

(b)

measure current

(c)

detect thermal radiation

(d)

measure pressure

Which one of the following is correct. According to Biot-Savart law, the magnetic induction is directly proportional to _________________.

(a)

Square of the current

(b)

Square root of the current

(c)

Length of the current element

(d)

Square of the distance

Diamagnetic materials

(1)

Pt, Cr, Mn

Paramagnetic materials

(2)

Steel, Alnico

Ferromagnetic materials

(3)

Bi, Sb, Cu

Permanent magnets

(4)

Applied for circular coil carrying current

Right hand thumb rule

(5)

Fe, Ni, Co etc.,