Archives

Time period of a simple pendulum is T inside a lift when the lift is stationary. If the lift moves upwards with an acceleration g/2, the time period of the pendulum will be:

a. b. c. d. Answer: (c) When lift is stationary A pseudo force will act downwards when the lift is accelerating upwards.... View Article

For an electromagnetic wave travelling in free space, the relation between average energy densities due to electric (U_e) and magnetic (U_m) fields is :

a. Ue ≠ Um b. Ue = Um c. Ue > Um d. Ue < Um Answer: (b) In EMW, the average energy density due to electric field (Ue) and magnetic field... View Article

For changing the capacitance of a given parallel plate capacitor, a dielectric material of dielectric constant K is used, which has the same area as the plates of the capacitor. The thickness of the dielectric slab is (¾) d, where ‘d’ is the separation between the plates of parallel plate capacitors. The new capacitance (C’) in terms of original capacitance (C0) is given by the following relation:

a. b. c. d. Answer: (a) C1 and C2 are in series and C’ is new capacitance Therefore, Therefore, Hence option (a)... View Article

The velocity-displacement graph describing the motion of a bicycle is shown in the figure.

The velocity-displacement graph describing the motion of a bicycle is shown in the figure. The acceleration-displacement graph of the... View Article

A conducting bar of length L is free to slide on two parallel conducting rails as shown in the figure. Two resistors R1 and R2 are connected across the ends of the rails. There is a uniform magnetic field → B pointing into the page. An external agent pulls the bar to the left at a constant speed v. The correct statement about the directions of induced currents I1 and I2 flowing through R1 and R2 respectively is : a. I1 is in the clockwise direction and I2 is in the anticlockwise direction b. Both I1 and I2 are in a clockwise direction c. I1 is in the anticlockwise direction and I2 is in a clockwise direction d. Both I1 and I2 are in the anticlockwise direction

Answer: (a) When the bar slides, the area of loop 1 decreases and that of loop 2 increases. Magnetic flux decreases in 1 and... View Article

The volume V of an enclosure contains a mixture of three gases, 16 g of oxygen, 28 g of nitrogen and 44 g of carbon dioxide at absolute temperature T. Consider R as a universal gas constant. The pressure of the mixture of gases is:

a.(4RT)/V b.(88RT)/V c.(5/2)(RT/V) d. 3RTV Answer: (c) No. of moles of O2 : n1=16/32=0.5 mole No. of moles of N2 : n2=28/28=1 mole No. of moles... View Article

The pressure acting on a submarine is 3×10⁵Pa at a certain depth. If the depth is doubled, the percentage increase in the pressure acting on the submarine would be :(Assume that atmospheric pressure is 1×10⁵ Pa, the density of water is 10³ kg m^–3, acceleration due to gravity g = 10 ms^–2)

a. (200/3)% b. (5/200)% c. (200/5)% d. (3/200)% Answer: (a) Pressure at depth h is P = P0 +hρg= 3×105 Pa ⇒ hρg =... View Article

A conducting wire of length ‘l’, area of cross-section A and electric resistivity ρ is connected between the terminals of a battery. A potential difference V is developed between its ends, causing an electric current. If the length of the wire of the same material is doubled and the area of cross-section is halved, the resultant current would be:

a. b. c. d. Answer: (d) We know that R=ρ(l/A) Now, new length: l'=2l The new area of cross-section: A'=A/2 Therefore, New... View Article

In thermodynamics, heat and work are:

In thermodynamics, heat and work are: a. Intensive thermodynamics state variables b. Extensive thermodynamics state variables c. Path functions... View Article

An RC circuit as shown in the figure

An RC circuit as shown in the figure is driven by an AC source generating a square wave. The output wave pattern monitored by CRO would look... View Article

A block of 200 g mass moves with a uniform speed in a horizontal circular groove, with vertical sidewalls of a radius of 20 cm. If the block takes 40 s to complete one round, the normal force by the sidewalls of the groove is:

a. 6.28 ×10–3 N b. 0.0314 N c. 9.859×10–2 N d. 9.859×10–4 N Answer: (d) Normal force will provide the... View Article

The maximum and minimum distances of a comet from the Sun are 1.6×10¹² m and 8.0×10¹⁰m respectively. If the speed of the comet at the nearest point is 6×10⁴ ms^–1, the speed at the farthest point is :

a. 1.5×103 m/s b. 4.5×103 m/s c. 3.0×103 m/s d. 6.0×103 m/s Answer: (c) Let point 1 is nearest point, and point 2... View Article

A plane electromagnetic wave of frequency 500 MHz is travelling in vacuum along y-direction. At a particular point in space and time,[latex]vec{B}=8.0times 10^{-8}hat{z}T[/latex]. The value of electric field at this point is: (speed of light = 3×10⁸ ms^–1) Assume x, y, z are unit vectors along [latex]hat{x}[/latex], [latex]hat{y}[/latex] and [latex]hat{z}[/latex] directions.

a. b. c. d. Answer: (d) E0 = B⋅C E0 = (8×10–8) × (3×108) ⇒ |E0| = 24 Wave travels in the... View Article

One main scale division of a vernier callipers is ‘a’ cm and n^th division of the vernier scale coincides with (n–1)^th division of the main scale. The least count of the callipers in mm is:

a. b.10a/n c.10na/(n-1) d. 10a/(n-1) Answer: (b) MSD → Main scale division VSD → Vernier scale division LC → Least count n VSD =... View Article

The stopping potential in the context of the photoelectric effect depends on the following property of incident electromagnetic radiation:

a. Amplitude b. Phase c. Frequency d. Intensity Answer: (c) According to Einstein's photoelectric equation, stopping potential depends on... View Article

Four equal masses, m each is placed at the corners of a square of length(l) as shown in the figure. The moment of inertia of the system about an axis passing through A and parallel to DB would be:

Four equal masses, m each is placed at the corners of a square of length(l) as shown in the figure. The moment of inertia of the system about an... View Article

A block of mass m slides along a floor while a force of magnitude F is applied to it at an angle θ as shown in the figure. The coefficient of kinetic friction is μ_K. Then, the block’s acceleration ‘a’ is given by (g is the acceleration due to gravity)

a. b. c. d. Answer: (a) Drawing the FBD of the block. ⇒ N = mg – Fsinθ …(1) Also, Fcosθ – μKN =... View Article

A 25 m long antenna is mounted on an antenna tower. The height of the antenna tower is 75 m. The wavelength (in meter) of the signal transmitted by this antenna would be:

a. 200 b. 400 c. 100 d. 300 Answer: (c) Given that, the height of the peak of the antenna: H = 25 m. As we know that λ = 4H Therefore,... View Article

The number of octahedral voids per lattice site in a lattice is __________.(Rounded off to the nearest integer)

Answer: 1 Assuming FCC No of lattice sites = 6 face centre + 8 corner = 14 No. of octahedral voids = 13 Ratio = 13/14 = 0.92857 = 1 (nearest... View Article

The pH of ammonium phosphate solution, if pk_a of phosphoric acid and pk_b of ammonium hydroxide are 5.23 and 4.75 respectively, is_____________.

Answer: 7 pH = pka + ½ {pkw - pka - pkb} pH = 5.23 + ½ {14–5.23–4.75} pH = 5.23 + ½ (4.02) = 7.24 =... View Article