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The wavelength of light used in an optical instrument is λ₁ = 4000 Angstrom and λ2 = 5000 Angstrom, then the ratio of their respective resolving powers (corresponding to λ₁ and λ₂) is

The inverse of the distance or angular separation between two objects which can be just resolved when viewed through the optical instrument is... View Article

Through two parallel wires A and B, 10A and 2A of currents are passed respectively in opposite directions. If the wire A is infinitely long and the length of the wire B is 2m, then force on the conductor B, which is situated at 10 cm distance from A, will be

We have two parallel current-carrying conductors, separated by a distance ‘d’, such that one of the conductors is carrying a... View Article

A black hole is an object whose gravitational field is so strong that even light cannot escape from it. To what approximate radius would earth (mass=5.98×10 24kg) have to be compressed to be a black hole?

Escape velocity is defined as the speed at which an object travels to break free from either the planet's or moon's gravity and leave... View Article

Which of the following forms a virtual and erect image of the same size for all positions of the object?
(a)Convex lens

(b)Plane mirror
(c) Convex mirror
(d)Concave mirror

The correct answer is (c) Convex mirror The convex mirror always forms an erect and diminished image. A convex mirror is a type of... View Article

Seven times a two digit number is equal to four times the number obtained by reversing the order of its digits.If the difference of the digits is 3. Find the number

Let us assume the number at one place be x the number at tens place be y So the number to obtain is in the form of 10y+x On reversing... View Article

If the distance of p(x,y) from a(5,1) and b(-1,5) are equal, prove that 3x = 2y.

Given that The point P(x, y) is equidistant from the points A(5, 1) and B(– 1, 5) Hence PA = PB or PA2 = PB2 The... View Article

A star is receding away from earth with a velocity of . if the wavelength of its spectral line is , then doppler shift will be

A Doppler shift is a phenomenon of a change in frequency based on the observer’s point of view. The most common analogy of this is... View Article

If velocity (v), time (t) and mass (m) are taken as fundamental quantities, then dimensional formula for gravitational potential would be___

Dimensional analysis is the practice of checking relations between physical quantities by identifying the dimensions of the physical quantities.... View Article

An electric current of 3 A passes through a wire of resistance 15 ω. How much heat will be developed in 1 minute?

Given An electric iron of resistance 15 Ω takes a current of 3 A Find out We have to calculate the heat developed in one minute or... View Article

The radii of curvature of the surfaces of a double convex lens are 20 cm and 40 cm respectively, and its focal length is 20 cm. What is the refractive index of the material of the lens?

The refractive index is the measure of bending of a light ray when passing from one medium to another. It can also be defined as the ratio of the... View Article

A time varying power P=2t is applied on a particle of mass m. Find kinetic energy and velocity of particle as function of time

Power is a physical concept with several different meanings, depending on the context and the available information. We can define power as the... View Article

Static electricity can be produced by______ (a) Only induction (b) Only friction (c)Only chemical reaction (d) Induction and friction

The correct answer is (d) Induction and friction Static electricity refers to an imbalance between the electric charges in a body,... View Article

A recurring deposit account of Rs 1,200 per month has a maturity value of Rs 12,440. If the rate of interest is 8% and the interest is calculated at the end of every month; find the time (in months) of this Recurring Deposit Account.

Given As per the given data P=Rs.1200 Nmberofmonths=n Intrest rate=8% MaturityAmount=Rs.12440 Find out We have to determine the... View Article

We wish to obtain same sized image of an object, using a concave mirror of focal length 15 cm. where should be the object placed from the mirror?

The real and inverted image produced by a concave mirror becomes of equal size to the object when both object and images are situated on the... View Article

A closed loop carrying current I lies in the x-z plane. The loop will experience a force if it is placed in a region occupied by a uniform magnetic field along: (a) x-axis (b) y-axis (c)z-axis (d) none of these

The correct answer is (d) none of these A closed loop carrying current I lies in the x-z plane. From the general equation we know that If the... View Article

The given figure gives a match stick pattern of triangles. Find the general rule that gives the number of matchsticks in terms of the number of triangles.

From the figure we observe that in the given matchstick pattern, the number of matchsticks are 3, 5, 7 and 9 which is 1 more than the twice... View Article

A cone, a hemisphere and a cylinder stand on equal bases of radius r and have equal heights h.Prove that their volumes are in the ratio 2:3:1

Given A cone, a hemisphere and a cylinder stand on equal bases of radius r and have equal heights h. To Prove We have to prove that their... View Article

The difference between a two digit number and the number obtained by the interchanging the digits is 27. What is the difference between the two digits of the number?

Given The difference between a two digit number and the number obtained by the interchanging the digits is 27 Find out We have to... View Article

In how many ways can 5 boys and 5 girls sit in a circle so that no two boys sit together?

Permutation relates to the act of arranging all the members of a set into some sequence or order. The combination is a way of selecting... View Article

Find out the correct option from the following. (a) The magnification is positive for all virtual images and is negative for all real images. (b) The magnification of the concave lens and convex mirror is always positive whereas the magnification of the convex lens and concave mirror can be positive or negative depending on the position of the object before the lens. A. Only (a) is true. B. Only (b) is true. C. Both (a) and (b) are true. D. Both (a) and (b) are false.

Magnification is the increase in the image size produced by spherical mirrors with respect to the object size. It is the ratio of the height of... View Article

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