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A length of wire carries a steady current. It is bent first to form a circular plane of coil of one turn. The same length is now bent more sharply to give a double loop of smaller radius. The magnetic field at the centre caused by the same current is (A) a quarter of its first value (B) unaltered (C) four times of its first value (D) half of its first value

Answer: (C) four times of its first value We know that the magnetic field is given as: ⇒ B = μ0nI/2R For the initial case, let us assume a... View Article

A galvanometer can be converted into a voltmeter by connecting: A. Low resistance in parallel B. Low resistance in series C. High resistance in parallel D. High resistance in series

Answer: D. High resistance in series A large resistance is connected in series with a galvanometer to convert it to a voltmeter. Because a... View Article

What is biasing a diode?

In general, biassing is described as a configuration in a diode or an electrical device that allows for a greater flow of current in one... View Article

Which of the following substances is antiferromagnetic? (a).MnO (b).CrO2 (c).Fe3O4 (d).NaCl

Answer: (a) MnO Antiferromagnetism is a property of MnO. Antiferromagnetism is a kind of solid magnetism in which neighbouring ions behave... View Article

The solubility product of Ag2CrO4 is 2.6×10⁻² at 25∘C. Calculate the solubility of the compound.

A precipitate may or may not occur when two electrolytic solutions are mixed. Two criteria are reviewed in order to assess whether a precipitate... View Article

Correct order of polarizing power is: A. Cs⁺ < K⁺ < Mg²⁺ < Al³⁺ B. Al³⁺ < Mg²⁺ <K⁺< Cs⁺ C. Mg²⁺ < Al³⁺ < K⁺< Cs⁺ D. K⁺ < Cs⁺ < Mg²⁺ < Al³⁺

Answer: (a) Polarising power is the extent to which a cation can polarise an anion. It is proportional to charge density. Charge density is... View Article

A particle has a displacement of 12 m towards east then 5 m towards north and then 6 m vertically upward. The resultant displacement is: A) 10.04 m B) 12.10 m C) 14.32 m D) 12.6 m

Given that d1=12m d2=5m d3=6m Now, we will find the resultant displacement of the particle due to its motion of 12 m towards east and 5 m... View Article

A long straight wire in the horizontal plane carries a current of 50A in north to south direction. Find the magnitude and direction of B at a point 2.5m east of the wire.

Formula used: B=μ0I/2πr. As we already know that for an infinite conductor, the magnetic field B at a perpendicular distance r is equal... View Article

The interstitial hole is called tetrahedral why?

Each sphere of the second layer touches three spheres of the first layer in hexagonal close packing (hcp) and cubic close packing (ccp). As a... View Article

An electric dipole of length 1cm which is kept with its axis making an angle of 60∘ with a uniform electric field, experiences a torque of 6√3Nm. Calculate the potential energy of the dipole if it has charge ±2nC.

The length of the electric dipole is given as, l = 1cm The angle at which the dipole is placed from the axis is given as, θ = 60∘... View Article

A concave mirror of focal length 10cm is placed at a distance of 35cm from a wall. How far from the wall should an object be placed so that its real image is formed on the wall?

Focal length of the mirror is 10 cm Distance of the object from the wall is 35 cm Now, we want to get the real image of the object on the wall.... View Article

A uniform but time varying magnetic field is present in a circular region of radius R. The magnetic field is perpendicular and into the plane of the loop and the magnetic field is increasing at a constant rate α.There is a straight conducting rod of length 2R placed as shown in figure. The magnitude of induced emf across the rod is:

Given that, Rate of change of magnetic field,dB/dt=α According to Faraday's law, emf induced in a closed loop is equal to the rate of change of... View Article

With reference to specifying the magnetic field, which of the following physical quantities is not an “element” of the earth’s magnetic field? A) Magnetic dip B) Vertical component of the field C) Magnetic declination D) Horizontal component of the field

answer: (c) vertical component of the field Earth’s magnetic field is also referred to as the geomagnetic field. The earth’s magnetic field... View Article

A uniform magnetic field B exists in a cylindrical region of radius 10cm as shown in figure. A uniform wire of length 80cm and resistance 4.0Ω is bent into a square frame and is placed with one side along a diameter of the cylindrical region. If the magnetic field increases at a constant rate of 0.010T/s, find the current induced in the frame.

A centripetal force is a net force acting on an item in order to maintain it moving in a circular motion. According to Newton's first rule of... View Article

Two identical wires A and B, each of length L, carry the same current I. Wire A is bent into a circle of radius R and wire B is bent to form a square of side ‘a’. If BA and BB are the values of magnetic field at the centre of the circle and square respectively, then what is the value of the ratio BA/BB

Both wires carry current I and are of length L. The magnetic field for a circle of radius R is given by B=μ0I/2R The length of wire A is L and... View Article

A metal sphere A of radius r1ncharged to a potential ϕ1 is enveloped by a thin walled conducting spherical shell B of radius r2. Then potential ϕ2of the sphere A after it is connected to the shell B by a thin conducting wire will be :-

The charge q1 can be obtained form q1 = uπϵ0ϕ1r1 After the connection, the entire charge q1 will How form the sphere to the enveloped and will... View Article

Cortisone is a molecular substance containing 21 atoms of carbon per molecule. The mass percentage of carbon in cortisone is 69.98%. What is the molecular mass of cortisone?

Let us consider we have 100g of cortisone that means that 100g of cortisone 69.98g is carbon, this is the information we get from the mass... View Article

In the arrangement shown, the pulleys and the strings are ideal. The acceleration of block B is

Let us consider that block A is moving up and block B is moving down For block A, From newton’s 2nd law of motion T1−mAg=mAa1 ……………………………(1)... View Article

A man slides down a light rope whose breaking strength is η times the weight of man (η<1) . The maximum acceleration of the man so that the rope just breaks is:

To find the equation between tension in the rope, weight of the man, and force due to acceleration of the man, we will first try to find the... View Article

In the cyanide extraction process of silver from argentite ore, the oxidizing and reducing agents used are:

Silver is going to be extracted from argentite ore by using the cyanide process. Other than cyanide, oxidising and reducing substances are... View Article

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