Part Test- 8 (JEE Main 2018) - JEE MCQ

A chain of mass m and length l is placed on a table with one-sixth of it hanging freely from the table
edge. The amount of work done to pull the chain on the table is-

A block of mass m slips down an inclined plane as shown in the figure. When it reaches the bottom it presses the spring by a length (spring length <<h and spring constant = K)-

A cylindrical cavity of diameter of a exists inside a cylinder of diameter 2a as shown in the figure. Both the cylinder and the cavity are infinitely long. A uniform current density J flows along the length.

If the magnitude of the magnetic field at the point P is given by 

A circular coil of radius a and having N turns is placed at centre of a long solenoid, coaxially. The
solenoid has radius b (b >> a) and number of turns per unit length is n. Their coefficient of mutual
inductance will be –

A long circular tube of length 10 m and radius 0.3 carries a current I along its curved surface as shown. A wire-loop of resistance 0.005 ohm and of radius 0.1 m is placed inside the tube with its axis coincidingwith the axis of the tube. The current varies as I = I₀ cos(300 t) where I₀ is constant.If the I magnetic moment of the loop is Nμ₀I₀ sin(300 t), then ‘N’ is.

A charge +Q at A (See figure) produces electric field E and electric potential V at D. If we now put
charges –2Q and +Q at B and C respectively, then the electric field and potential at D will be -

A blackbody, at a high temperature T, radiates energy at the rate of U(in W/m²). When the
temperature falls to half (i.e., T/2), the radiated energy (in W/m²) will be :

Three identical thermal conductors are, connected as shown in figure. Considering no heat loss due to radiation, temperature at the junction will be -

Two identical rods AC and CB made of two different metals having thermal conductivities in the ratio 2 : 3 are kept in contact with each other at the end C as shown in the figure. A is at 100ºC and B is at 25ºC. Then the junction C is at -

A composite metal bar of uniform section is made up of length 25 cm of copper, 10 cm of nickel and 15 cm of aluminium. Each part being in perfect thermal contact with the adjoining part. The copper end of the composite rod is maintained at 100ºC and the aluminium end at 0ºC. The whole rod is covered, so that no heat loss occurs at the sides. If K_Cu = 2K_Al and K_Al = 3K_Ni, then what will be the temperature of Cu-Ni and Ni-Al junctions respectively -

The ratio of the coefficient thermal conductivity of two different materials is 5 : 3. If the thermal
resistance of the rods of same thickness of these materials is same, then the ratio of the length of
these rods will be -

A force F = Ay² + By + C acts on a body in the y-direction. The work done by this force during a
displacement from y = –a to y = a is

Carbon-14 decay with a half life of about 5,800 year. In a sample of bone, the ratio of carbon-14 to
carbon-12 is found to be 1/4 of what it is in free air. This bone may belong to period about x centuries ago, where x is

The Boolean equation for the circuit given in figure is

A light emitting diode (LED) has a voltage drop of 2V across it and passes a current of 10 mA. When
it operates with a 6V battery through a limiting resistor R, the value of R is :

In the network shown in figure :

(a) the potential difference across D₂ is 5 V
(b) current through resistor equals 1.25 A
(c) current through diode D₁ is 1.25 A
(d) current through diode D₂ is 1.25A

A telescope has an objective lens of 10 cm diameter and is situated at a distance of 1 km from two
objects. The minimum distance between these two objects, which can be resolved by the telescope,
when the mean wavelength of light is is of the order of

In a Young’s double slit experiment, λ = 500 nm, d = 1.0 mm and D = 1.0 m. Find the minimum
distance from the central maximum for which the intensity is half of the maximum intensity

In a double slit experiment, two coherent sources have slightly different intensities
I and (I + δI), such that δI < < I. Then I_min/I_max will be

Light incident on a surface separating two media is partly reflected and partly refracted as shown in the figure. Then:

In the figure shown for resistance of R₁ and R₂ the balance point for jockey is at 40 cm from A.
when R₂ is shunted by a resistance of 10 , balance shifts to 50 cm. R₁ and R₂ are (AB = 1m)-

A heater A gives out 300 W of heat when connected to a 200 V d.c. supply. A second heater B gives out 600 W when connected to a 200 V d.c. supply. If a series combination of the two heaters is connected to a 200 V d.c. supply the heat output will be -

In the given potentiometer circuit, the resistance of the potentiometer wire AB is R₀. C is a cell of
internal resistance r. The galvanometer G does not give zero deflection for any position of the
jockey J. Which of the following cannot be a reason for this ?

The current I in the circuit shown in the figure is -

A particle is released from a height H. At certain height its kinetic energy is two times its potential
energy. Height and speed of particle at that instant are

A car of mass m is accelerating on a level smooth road under the action of a single force F. The power delivered to the car is constant and equal to P. If the velocity of the car at an instant is v, then after
travelling how much distance it becomes double ?

A small block of mass m is kept on a rough inclined surface of inclination ? fixed in an elevator. The
elevator goes up with a uniform velocity v and the block does not slide on the wedge. The work
done by the force of friction on the block in a time t will be