JEE MAIN - Physics (2013 (Offline))

• 1

  Diameter of a plano-convex lens is $$6$$ $$cm$$ and thickness at the center is $$3mm$$. If speed of light in material of lens is $$2 \times {10^8}\,m/s,$$ the focal length of the lens is

  Svare

  (C)

  $$30$$ $$cm$$
• 2

  A circular loop of radius $$0.3$$ $$cm$$ lies center of the small loop is on the axis of the bigger loop. The distance between their centers is $$15$$ $$cm.$$ If a current of $$2.0$$ $$A$$ flows through the smaller loop, than the flux linked with bigger loop is

  Svare

  (A)

  $$9.1 \times {10^{ - 11}}\,$$ weber
• 3

  Two short bar magnets of length $$1$$ $$cm$$ each have magnetic moments $$1.20$$ $$A{m^2}$$ and $$1.00$$ $$A{m^2}$$ respectively. They are placed on a horizontal table parallel to each other with their $$N$$ poles pointing towards the South. They have a common magnetic equator and are separated by a distance of $$20.0$$ $$cm.$$ The value of the resultant horizontal magnetic induction at the mid-point $$O$$ of the line joining their centres is close to $$\left( \, \right.$$ Horizontal component of earth's magnetic induction is $$3.6 \times 10.5Wb/{m^2})$$

  Svare

  (B)

  $$2.56 \times 10.4\,\,Wb/{m^2}$$
• 4

  Statement - $${\rm I}$$ : Higher the range, greater is the resistance of ammeter.
  Statement - $${\rm I}$$$${\rm I}$$ : To increase the range of ammeter, additional shunt needs to be used across it.

  Svare

  (D)

  Statement - $${\rm I}$$ is false, Statement - $${\rm II}$$ is true
• 5

  The magnetic field in a travelling electromagnetic wave has a peak value of $$20$$ $$n$$$$T$$. The peak value of electric field strength is :

  Svare

  (B)

  $$6V/m$$
• 6

  A diode detector is used to detect an amplitude modulated wave of $$60\% $$ modulation by using a condenser of capacity $$250$$ picofarad in parallel with a load resistance $$100$$ kilo $$ohm.$$ Find the maximum modulated frequency which could be detected by it.

  Svare

  (B)

  $$10.62$$ $$kHz$$
• 7

  The graph between angle of deviation $$\left( \delta \right)$$ and angle of incidence $$(i)$$ for a triangular prism is represented by

  Svare

  (C)

  
• 8

  Two coherent point sources $${S_1}$$ and $${S_2}$$ are separated by a small distance $$'d'$$ as shown. The fringes obtained on the screen will be
  
  

  Svare

  (D)

  concentric circles
• 9

  In an $$LCR$$ circuit as shown below both switches are open initially. Now switch $${S_1}$$ is closed, $${S_2}$$ kept open. ($$q$$ is charge on the capacitor and $$\tau $$ $$=RC$$ is Capacitance time constant). Which of the following statement is correct ?

  Svare

  (C)

  At $$t = \,2\tau ,\,q = CV\left( {1 - {e^{ - 2}}} \right)$$
• 10

  A metallic rod of length $$'\ell '$$ is tied to a string of length $$2$$$$\ell $$ and made to rotate with angular speed $$w$$ on a horizontal table with one end of the string fixed. If there is a vertical magnetic field $$'B'$$ in the region, the $$e.m.f$$ induced across the ends of the rod is

  Svare

  (D)

  $${{5B\omega {\ell ^2}} \over 2}$$
• 11

  Diameter of a plano-convex lens is $$6$$ $$cm$$ and thickness at the center is $$3mm$$. If speed of light in material of lens is $$2 \times {10^8}\,m/s,$$ the focal length of the lens is

  Svare

  (C)

  $$30$$ $$cm$$
• 12

  A circular loop of radius $$0.3$$ $$cm$$ lies center of the small loop is on the axis of the bigger loop. The distance between their centers is $$15$$ $$cm.$$ If a current of $$2.0$$ $$A$$ flows through the smaller loop, than the flux linked with bigger loop is

  Svare

  (A)

  $$9.1 \times {10^{ - 11}}\,$$ weber
• 13

  Two short bar magnets of length $$1$$ $$cm$$ each have magnetic moments $$1.20$$ $$A{m^2}$$ and $$1.00$$ $$A{m^2}$$ respectively. They are placed on a horizontal table parallel to each other with their $$N$$ poles pointing towards the South. They have a common magnetic equator and are separated by a distance of $$20.0$$ $$cm.$$ The value of the resultant horizontal magnetic induction at the mid-point $$O$$ of the line joining their centres is close to $$\left( \, \right.$$ Horizontal component of earth's magnetic induction is $$3.6 \times 10.5Wb/{m^2})$$

  Svare

  (B)

  $$2.56 \times 10.4\,\,Wb/{m^2}$$
• 14

  Statement - $${\rm I}$$ : Higher the range, greater is the resistance of ammeter.
  Statement - $${\rm I}$$$${\rm I}$$ : To increase the range of ammeter, additional shunt needs to be used across it.

  Svare

  (D)

  Statement - $${\rm I}$$ is false, Statement - $${\rm II}$$ is true
• 15

  The supply voltage to room is $$120V.$$ The resistance of the lead wires is $$6\Omega $$. A $$60$$ $$W$$ bulb is already switched on. What is the decrease of voltage across the bulb, when a $$240$$ $$W$$ heater is switched on in parallel to the bulb?

  Svare

  (D)

  $$10.04$$ Volt
• 16

  A charge $$Q$$ is uniformly distributed over a long rod $$AB$$ of length $$L$$ as shown in the figure. The electric potential at the point $$O$$ lying at distance $$L$$ from the end $$A$$ is

  Svare

  (D)

  $${{Q\ln \,2} \over {4\pi {\varepsilon _0}L\,{}^s}}$$
• 17

  A charge $$Q$$ is uniformly distributed over a long rod $$AB$$ of length $$L$$ as shown in the figure. The electric potential at the point $$O$$ lying at distance $$L$$ from the end $$A$$ is

  Svare

  (D)

  $${{Q\ln \,2} \over {4\pi {\varepsilon _0}L\,{}^s}}$$
• 18

  Two charges, each equals to $$q,$$ are kept at $$x=-a$$ and $$x=a$$ on the $$x$$-axis. A particle of mass $$m$$ and charge $${q_0} = {q \over 2}$$ is placed at the origin. If charge $${q_0}$$ is given a small displacement $$\left( {y < < a} \right)$$ along the $$y$$-axis, the net force acting on the particle is proportional to

  Svare

  (A)

  $$y$$
• 19

  A sonometer wire of length $$1.5$$ $$m$$ is made of steel. The tension in it produces an elastic strain of $$1\% $$. What is the fundamental frequency of steel if density and elasticity of steel are $$7.7 \times {10^3}\,kg/{m^3}$$ and $$2.2 \times {10^{11}}\,N/{m^2}$$ respectively ?

  Svare

  (B)

  $$178.2$$ $$Hz$$
• 20

  An ideal gas enclosed in a vertical cylindrical container supports a freely moving piston of mass $$M.$$ The piston and the cylinder have equal cross sectional area $$A$$. When the piston is in equilibrium, the volume of the gas is $${V_0}$$ and its pressure is $${P_0}.$$ The piston is slightly displaced from the equilibrium position and released,. Assuming that the system is completely isolated from its surrounding, the piston executes a simple harmonic motion with frquency

  Svare

  (C)

  $${1 \over {2\pi }}\,\sqrt {{{A\gamma {P_0}} \over {{V_0}M}}} $$
• 21

  

  The above $$p$$-$$v$$ diagram represents the thermodynamic cycle of an engine, operating with an ideal monatomic gas. The amount of heat, extracted from the source in a single cycle is

  Svare

  (B)

  $$\left( {{{13} \over 2}} \right){p_0}{v_0}$$
• 22

  Assume that a drop of liquid evaporates by decreases in its surface energy, so that its temperature remains unchanged. What should be the minimum radius of the drop for this to be possible ? The surface tension is $$T,$$ density of liquid is $$\rho $$ and $$L$$ is its latent heat of vaporization.

  Svare

  (D)

  $$2T/\rho L$$
• 23

  A uniform cylinder of length $$L$$ and mass $$M$$ having cross-sectional area $$A$$ is suspended, with its length vertical, from a fixed point by a mass-less spring such that it is half submerged in a liquid of density $$\sigma $$ at equilibrium position. The extension $${x_0}$$ of the spring when it is in equilibrium is:

  Svare

  (C)

  $${{Mg} \over k}\left( {1 - {{LA\sigma } \over {2M}}} \right)$$
• 24

  What is the minimum energy required to launch a satellite of mass $$m$$ from the surface of a planet of mass $$M$$ and radius $$R$$ in a circular orbit at an altitude of $$2R$$?

  Svare

  (A)

  $${{5GmM} \over {6R}}$$
• 25

  A hoop of radius $$r$$ and mass $$m$$ rotating with an angular velocity $${\omega _0}$$ is placed on a rough horizontal surface. The initial velocity of the center of the hoop is zero. What will be the velocity of the center of the hoop when it cases to slip?

  Svare

  (C)

  $${{r{\omega _0}} \over 2}$$
• 26

  Statement - $${\rm I}$$: A point particle of mass $$m$$ moving with speed $$\upsilon $$ collides with stationary point particle of mass $$M.$$ If the maximum energy loss possible is given as $$f\left( {{1 \over 2}m{v^2}} \right)$$, then $$f = \left( {{m \over {M + m}}} \right).$$
  
  Statement - $${\rm II}$$: Maximum energy loss occurs when the particles get stuck together as a result of the collision.

  Svare

  (D)

  Statement - $${\rm I}$$ is false, Statement - $${\rm II}$$ true.
• 27

  A projectile is given an initial velocity of $$\left( {\widehat i + 2\widehat j} \right)$$ m/s, where $${\widehat i}$$ is along the ground and $${\widehat j}$$ is along the vertical. If g = 10 m/s², the equation of its trajectory is:

  Svare

  (B)

  y = 2x - 5x²
• 28

  Let [$${\varepsilon _0}$$] denote the dimensional formula of the permittivity of vacuum. If M = mass, L = length, T = time and A = electric current, then:

  Svare

  (B)

  $${\varepsilon _0} = $$$$\left[ {{M^{ - 1}}{L^{ - 3}}{T^4}{A^2}} \right]$$