Online Mock Test Series for NEET 2020 19 A capacitor of capacitance 1 F is charged to 30 V and the battery is then disconnected If it is connected across a 2 F capacitor the energy lost by the system is 1 300 J 2 450 J 4 150 J 3 100 J 20 A particle is moving along a circular path of radius 10 m with a uniform speed 10 m s What will be the average acceleration when the particle completes half revolution 1 10 It m s 20 2 IL 4 Zero 1 2uF 3 4 F 3 10 m s 21 A capacitor having capacitance 1 F with air is filled with two dielectrics as shown Now capacitance of the system is K 2 2 3 F 4 5 F m s 22 A sonometer wire supports a 4 kg load and vibrates in fundamental mode with a tuning fork of frequency 416 Hz The length of the wire between the bridges is now doubled In order to maintain fundamental mode the load should be changed to 1 2 kg 2 8 kg 3 16 kg 4 4 kg 23 A carnot engine has efficiency becomes F when temperature of sir is decreased by 50 K What was the temperature of the sink 1 375 K 3 300 K 24 The pressure P versus density p of a given mass of an ideal gas is shown at two different temperatures T and T 2 325 K 4 350 K T Then relation between T and T T Efficiency 1 T T 2 T T 3 T T 26 4 All the three are possible 25 Sodium and copper have work functions 2 3 eV and 4 6 eV respectively Then the ratio of their threshold wavelengths is nearest to 1 1 2 2 2 1 4 4 1 3 1 4 In Young s double slit experiment if the intensity at the centre of screen is then intensity at a distance from the central maxima is here B fringe width 1 3 Ala Im A 27 The reading of the ammeter in the given figure will be A 40 3 V Vo 60 R 2u R im R 2u R 60 602 www 4V N 12 e w o Test 4 Code A 2 3 4 1 A 28 A luminous point is moving at speed v towards a spherical mirror along its axis Then the speed at which the image of this point object is moving is given by R Radius of curvature and u object distance 1 V Vo WIN A 2 v V 4 V Vo 2u R R