Two rigid boxes containing different ideal gases are placed on a table. Box A contains one mole of nitrogen at temperature T₀, while Box B contains one mole of helium at temperature (7/3) T₀. The boxes are then put into thermal contact with each other and heat flows between them until the gases reach a common final temperature. (Ignore the heat capacity of boxes). Then, the final temperature of the gases, T_f, in terms of T₀ is

The Kirchhoff’s first law (∑ i= 0)   and second law (∑iR = ∑E), where the symbols have their usual meanings, are respectively based on

• conservation of charge, conservation of energy

• conservation of charge, conservation of momentum

• conservation of energy, conservation of charge

• conservation of energy, conservation of charge

Needles N₁, N₂ and N₃ are made of a ferromagnetic, a paramagnetic and a diamagnetic substance respectively. A magnet when brought close to them will

• attract all three of them

• attract N₁ and N₂ strongly but repel N₃

• attract N₁ strongly, N₂ weakly and repel N₃ weakly

• attract N₁ strongly, N₂ weakly and repel N₃ weakly

A material ‘B’ has twice the specific resistance of ‘A’. A circular wire made of ‘B’ has twice the diameter of a wire made of ‘A’. Then for the two wires to have the same resistance, the ratio

• 2

• 1

• 1/4

• 1/4

In a region, steady and uniform electric and magnetic fields are present. These two fields are parallel to each other. A charged particle is released from rest in this region. The path of the particle will be a

• circle

• helix

• straight line

• straight line

An electric dipole is placed at an angle of 30° to a non-uniform electric field. The dipole will experience

• a torque only

• a translational force only in the direction of the field

• a translational force only in a direction normal to the direction of the field

• a translational force only in a direction normal to the direction of the field

27.

In a Wheatstone’s bridge, there resistances P, Q and R connected in the three arms and the fourth arm is formed by two resistances S₁ and S₂ connected in parallel. The condition for bridge to be balanced will be

• 
• 
• 
• 

The current I drawn from the 5 volt source will be

• 0.17 A

• 0.33 A

• 0.5 A

• 0.5 A

In a series resonant LCR circuit, the voltage across R is 100 volts and R = 1 kΩ with C = 2µF. The resonant frequency ω is 200 rad/s. At resonance the voltage across L is

• 4 × 10−3 V

• 2.5 × 10⁻² V

• 40 V

• 40 V

Two insulating plates are both uniformly charged in such a way that the potential difference between them is V₂ −V₁ = 20 V. (i.e. plate 2 is at a higher potential). The plates are separated by d = 0.1 m and can be treated as infinitely large. An electron is released from rest on the inner surface of plate 1. What is its speed when it hits plate 2?


(e = 1.6 × 10⁻¹⁹ C, me = 9.11 × 10⁻³¹ kg)

• 32 × 10⁻¹⁹ m/s

• 2.65 × 10⁶ m/s

• 7.02 × 10¹² m/s

• 7.02 × 10¹² m/s