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If the magnitude of two vectors are 4 and 6 and the magnitude of their scalar product is 12√2 , then what is the angle between these vectors?

A vector is a two-dimensional entity with both magnitude and direction. A vector can be visualised geometrically as a directed line segment with... View Article

A potential difference V is applied across a conductor of length ‘l’. How is the drift velocity affected when V is doubled and l is halved?

The formula for drift velocity is given by, |vd|=eτ/m x E But we know that E=V/l where V is the potential difference and l is the length... View Article

Assertion: In javelin throw, the athlete throws the projectile at an angle more than 45∘. Reason: The maximum range does not depend upon angle of projection. (A) Both assertion and reason are the correct answer, reason is the correct explanation for assertion. (B) Both assertion and reason are correct. The answer reason is the incorrect explanation for the assertion. (C) Assertion is correct and reason is incorrect. (D) Both assertion and reason are incorrect.

A javelin's route is identical to that of a projectile motion. So the formula of range in projectile motion is applicable. R=u2sin2θ/g sinθ... View Article

A current carrying power line carries current from west to east .The direction of magnetic field 1m above is:

Answer: North to south The direction of the magnetic field surrounding a straight current carrying wire is determined by the curling of the... View Article

Two identical glass (μg =3/2) equiconvex lenses of focal length f are kept in contact. The space between the two lenses is filled with water (μw =4/3). The focal length of the combination is

Water in between the lens can be considered to be a concave lens of refractive index of water as shown in the figure. This suggests that the... View Article

An AC current is given by I = I₀ + I₁ sinωt then the rms value will be.

Alternating current is the current whose magnitude varies with time and reverse it direction periodically, i.e. after half-time period. The rms... View Article

The resultant force on the square current loop PQRS due to a long current-carrying conductor will be:

The forces will be equal and opposed because the currents in the lengths PQ and RS are equal and opposite. As a result, both will cancel each... View Article

An equilateral triangular loop of wire of side ℓ carries a current i. The magnetic field produced at the circumcentre of the loop is :

If considered l is the triangle's side, the circumcenter's distance from each of the triangle's sides equals r= I√3/6. The magnetic induction... View Article

Two Magnets of equal magnetic moments M each are placed as shown in figure. The resultant magnetic moment isa) M b) √2M c) √3M d) M/2

Answer: (a)M Due to the fact that magnetic moments are directed along SN, the angle between M and M is equal to θ=120o (from given figure)... View Article

What is the correct relation between common base current gain α and common emitter current gain β ?

Answer: β = α/1−α We have asked to determine the relationship between the current gain α in Common Base CB mode and the current gain β in... View Article

The stationary waves are produced in a 20 m long stretched string fixed at both ends. if the string vibrates in 10 loops and wave velocity in the string is 20 m/s, then the frequency of the wave is ?

The standing waves are formed by the superposition of two harmonic waves of equal amplitude and frequency travelling through the medium in the... View Article

The network shown in the figure is part of a complete circuit. If at a certain instant, the current I is 5A and it is decreasing at a rate of 10³As⁻¹ then VB−VA equals

As we move from point A to point B, we'll construct the voltage drop equation. VA − iR + V + L di/dt = VB VA−5 × 1 + 15 − 5 × 10−3 × (−103) =... View Article

For an RLC circuit driven with voltage of amplitude v_m and frequency ω₀= 1/√LC the current exhibits resonance. The quality factor, Q is given by. a) R/ω₀C b) CR/ω₀ c) ω₀L/R d) ω₀R/L

Answer: (c) The quality factor is defined as the voltage magnification of the circuit at resonance Quality Factor Q = 1/R √L/C It is... View Article

A conducting loop is placed in a uniform magnetic field, with its plane perpendicular to the field. An emf is induced in the loop if a) It is rotated about its axis b) It is rotated about its diameter c) It is not moved d) It is given translational motion in the field

Answer: B Only when the magnetic flux in the loop changes does an emf occur. When the loop is revolved around a diameter, this is... View Article

A body of mass 5 kg is suspended by a spring balance on an inclined plane as shown in figure. The spring balance measure

Acceleration of the body down the rough inclined plane =gsinθ ∴ Force applied on spring balance =m g sinθ = 5 × 10... View Article

A capacitor of capacitance C is charged to a potential difference V from a cell and then disconnected from it. A charge + Q is now given to its positive plate. The potential difference across the capacitor is now :

The capacitor's initial charge is q=CV. As a result, the capacitor's positive plate will receive a charge of +q, while the negative plate will... View Article

If A lies in the third quadrant and 3tanA – 4 = 0 then 5sin2A + 3sinA + 4cosA is equal to (1) 0 (2) -24/5 (3) 24/5 (4) 48/5

Answer: (1) 0 3tanA - 4 = 0 3tanA = 4 tanA = 4/3 tan2A = 16/9 sec2A = 1 + tan2A sec2A = 1 + 16/9 = 25/9 Since A lies in third quadrant... View Article

Which of the following chemical compound is planar? (1) XeF2 (2) XeO3F (3) XeO2F2 (4) XeF4

Answer: (4) XeF4 XeF4 is square planar molecule having two non-bonding electron pair, one is located above and one is located below the plane... View Article

A particle of charge q, mass m and kinetic energy T enters a transverse uniform magnetic field of induction B. After 3 s, the kinetic energy of the particle will be (1) 3T (2) 2T (3) T (4) 4T

Answer: (3) T Magnetic field does not change the kinetic energy of charged particles. So, the energy will be T. The magnitude of the particle's... View Article

A person of mass m is standing on one end of a plank of mass M and length L and floating in water. The person moves from one end to another and stops. The displacement of the plank is (1) Lm/(m + M) (2) L(M + m) (3) (M + m)/Lm (4) LM/(m + M)

Answer: (1) Lm/(m + M) Let Displacement of plank is x Velocity of person with respect to plank is v Velocity of plank is opposite... View Article

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