The negative Zn pole of a Daniell cell, sending a constant current through a circuit, decreases in mass by 0.13 g in 30 minutes. If the electrochemical equivalent of Zn and Cu are 32.5 and 31.5 respectively, the increase in the mass of the positive Cu pole in this time is

Anonymous User Physics Thermal and Chemical Effects of Current 14 Apr, 2020 1 Answer 65 views

The thermo e.m.f. of a thermo­couple is at room temperature. A galvanometer of 40 ohm resistance, capable of detecting current as low as 10-5 A, is connected with the thermocouple. The smallest temperature difference that can be detected by this system is

Anonymous User Physics Thermal and Chemical Effects of Current 14 Apr, 2020 1 Answer 66 views














 

 

The figure shows the velocity and acceleration of a point like body at the initial moment of its motion. The acceleration vector of the body remains constant. The minimum radius of curvature of trajectory of the body is?The figure shows the velocity and acceleration of a point like body at the initial moment of its motion. The acceleration vector of the body remains constant. The minimum radius of curvature of trajectory of the body is?

 

Anonymous User Physics 12 Apr, 2020 1 Answer 83 views


Two friends have equal number of sons. There are 3 tickets for a cricket match which are to be distributed among the sons. The probability that two tickets go to the sons of one and one tickets goes to the sons of other is 6 . Then total number of boys is equal to (sum of son of each friend).

Anonymous User Maths Probability 12 Apr, 2020 1 Answer 81 views





A wire when connected to 220 V mains supply has power dissipation P1. Now the wire is cut into two equal pieces which are connected in parallel to the same supply. Power dissipation in this case is P2. Then what will be P2 : P?

Anonymous User Physics Thermal and Chemical Effects of Current 12 Apr, 2020 1 Answer 63 views





The radiation corresponding to 3 → 2 transition of hydrogen atom falls on a metal surface to produce photoelectrons. These electrons are made to enter a magnetic field of 3 × 10−4 T. If the radius of the largest circular path followed by these electrons is 10.0 mm, the work function of the metal is close to :

Anonymous User Physics 11 Apr, 2020 1 Answer 73 views

Three rods of Copper, Brass and Steel are welded together to form a Y-shaped structure. Area of cross- section of each rod = 4 cm2. End of copper rod is maintained at 100 °C where as ends of brass and steel are kept at 0 °C. Lengths of the copper, brass and steel rods are 46, 13 and 12 cms respectively. The rods are thermally insulated from surroundings except at ends. Thermal conductivities of copper, brass and steel are 0.92, 0.26 and 0.12 CGS units respectively. Rate of heat flow through copper rod is :

Anonymous User Physics 11 Apr, 2020 1 Answer 67 views

A green light is incident from the water to the air - water interface at the critical angle (θ). Select the correct statement.

(1) The spectrum of visible light whose frequency is more than that of green light will come out to the air

medium.
(2) The entire spectrum of visible light will come out of the water at various angles to the normal.
(3) The entire spectrum of visible light will come out of the water at an angle of 90° to the normal.
(4) The spectrum of visible light whose frequency is less than that of green light will come out to the air

medium.

Anonymous User Physics 11 Apr, 2020 1 Answer 80 views

From a tower of height H, a particle is thrown vertically upwards with a speed U. The time taken by the particle, to hit the ground, is n times that taken by it to reach the highest point of its path. The relation between H, u and n is :

Anonymous User Physics 11 Apr, 2020 1 Answer 89 views

One mole of diatomic ideal gas undergoes a cyclic process ABC as shown in figure. The process BC is adiabatic. The temperatures at A, B and C are 400 K, 800 K and 600 K respectively. Choose the correct statement :

One mole of diatomic ideal gas undergoes a cyclic process ABC as shown in figure. The process BC is adiabatic. The temperatures at A, B and C are 400 K, 800 K and 600 K respectively

(1) The change in internal energy in the process AB is − 350 R.

(2) The change in internal energy in the process BC is − 500 R.
(3) The change in internal energy in whole cyclic process is 250 R.

(4) The change in internal energy in the process CA is 700 R.

Anonymous User Physics 11 Apr, 2020 1 Answer 73 views


During the propagation of electromagnetic waves in a medium : (1) Electric energy density is equal to the magnetic energy density. (2) Both electric and magnetic energy densities are zero. (3) Electric energy density is double of the magnetic energy density. (4) Electric energy density is half of the magnetic density.

Anonymous User Physics 11 Apr, 2020 1 Answer 86 views

The coercivity of a small magnet where the ferromagnet gets demagnetized is 3 × 103 A m−1. The current required to be passed in a solenoid of length 10 cm and number of turns 100, so that the magnet gets demagnetized when inside

Anonymous User Physics 11 Apr, 2020 1 Answer 70 views



A student measured the length of a rod and wrote it as 3.50 cm. Which instrument did he use to measure it ? (1) A screw gauge having 100 divisions in the circular scale and pitch as 1 mm. (2) A screw gauge having 50 divisions in the circular scale and pitch as 1 mm. (3) A meter scale. (4) A vernier calliper where the 10 divisions in vernier scale matches with 9 division in main scale & main scale has 10 divisions in 1 cm.

Anonymous User Physics 10 Apr, 2020 1 Answer 92 views

A parallel plate capacitor is made of two circular plates separated by a distance of 5 mm and with a dielectric of dielectric constant 2.2 between them. When the electric field in the dielectric is 3*10^4 V/m, the charge density of the positive plate will be close to :

Anonymous User Physics Capacitors 10 Apr, 2020 1 Answer 65 views

The pressure that has to be applied to the ends of a steel wire of length 10 cm to keep its length constant when its temperature is raised by 100°C is :
(For steel Young’s modulus is 2 × 10^11 N m−2 and coefficient of thermal expansion is 1.1 × 10^−5 K^−1)

Anonymous User Physics Wave Optics 10 Apr, 2020 1 Answer 78 views







Consider a block of conducting material of resistivity shown in the figure. Current I enters at A and leaves from D. We apply the superposition principle to find voltage  developed between B and C. The calculation is done in the following steps:

(i) Take current I entering from A and assume it to spread over a hemispherical surface in the block.

(ii) Calculate field E(r) at distance r from A by using Ohm’s law  where j is the current per unit area at r.

(iii) From the r dependence of E(r), obtain the potential V(r) at r.

(iv) Repeat (i), (ii) and (iii) for current I leaving and superpose results for A and D.

For current entering at A, the electric field at a distance r from A is

Anonymous User Physics Current Electricity 10 Apr, 2020 1 Answer 63 views

Consider a block of conducting material of resistivity shown in the figure. Current I enters at A and leaves from D. We apply the superposition principle to find voltage  developed between B and C. The calculation is done in the following steps:

(i) Take current I entering from A and assume it to spread over a hemispherical surface in the block.

(ii) Calculate field E(r) at distance r from A by using Ohm’s law  where j is the current per unit area at r.

(iii) From the r dependence of E(r), obtain the potential V(r) at r.

(iv) Repeat (i), (ii) and (iii) for current I leaving and superpose results for A and D.

 measured between B and C is

Anonymous User Physics Current Electricity 10 Apr, 2020 1 Answer 72 views


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 l/ lA of their respective lengths must be

Anonymous User Physics Current Electricity 10 Apr, 2020 1 Answer 116 views