Two resistors whose value are in ratio 2:1 are connected in parallel with one cell. Then ratio of power dissipated is
The heat developed is given by H = V2t/R ⇒ HHalf/Hfull = (RFull/RHalf) = R/R/2 = 2 Therefore, HHalf = 2 ×... View Article
Latest Posts
A conducting rod of length l is hinged at point O. It is free to rotate in a vertical plane. There exists a uniform magnetic field B in horizontal direction. The rod is released from the position. What is the potential difference between the two ends of the rod is proportional to?
The gravitational potential decreases to increase the kinetic energy of the rod. The equation can be written as, mg 1/2sinθ = 1/2Iω2 =... View Article
The angle of dip at a place is δ. If the dip is measured in a plane making an angle θ with the magnetic meridian, the apparent angle of dip δ1 will be :
Let δ1 be the angle of dip when dip circle is in magnetic meridian tanδ1=V/H The dip circle when makes an angle θ ,... View Article
A photoelectric cell is illuminated by a point source of light 1m away. What happens when the source is shifted to 2m?
The intensity of light is exactly proportional to the number of photoelectrons released each second. The light source’s intensity is... View Article
An electron moves in a circle of radius of 1.0cm with a constant speed of 4.0106m/s, electric current at a point on the circle will be: (e=−1.6×10−19C)
Given that the radius of circle R=1.0cm. Speed of electron along the circular path=4.0×106m/s. Constant value of electron or charge... View Article
A bar magnet of magnetic moment M is placed in the magnetic field B. The torque acting on the magnet is:
A pair force is made up of two parallel forces that have the same magnitude but opposing directions and do... View Article
If a wire of resistance R = 10ohm is stretched to double of its length, then new resistance will be:
The expression for the resistance of a wire is given as, R = ρ l/A where, ρ is the resistivity... View Article
Show on a graph, the variation of resistivity with temperature for a typical semiconductor.
The resistivity is given by: ρ=m/ne2τ where n= Number density of electrons τ= Relaxation time With the rise in temperature,... View Article
A particle moves on a circle of radius r with centripetal acceleration as function of time as ac=k2rt2 where k is a positive constant .Find the following quantities as a function of time at an instant. (A) The speed of the particle. (B) The tangential acceleration of the particle (C) the resultant acceleration and (D) Angle made by the resultant with tangential direction
Now we know that the magnitude of centripetal acceleration is given by, ac=v2/r where, v is the linear velocity of... View Article
An atomic power nuclear reactor can deliver 300 MW. The energy released due to fission of each nucleus of uranium atom U238 is 170 MeV. The number of uranium atoms fissioned per hour will be:-
Nuclear Energy is the energy in the core of an atom. Where an atom is a tiny particle that constitutes... View Article
Five point charges, each of value +q are placed on five vertices of a regular hexagon of side L. What is the magnitude of the force on a point charge of value −q placed at the centre of the hexagon?
Among the five forces on five charges,2pairs (four) of forces are cancelled with each other since they are equal in... View Article
On a 60km track, a train travels the first 30km with a speed of 30kmh−1 . How fast must the train travel the next 30km so as to average 40kmh−1 for the whole trip?
It is given that the first 30km is traveled with the speed 30kmh−1 , let us consider that the speed... View Article
The mass of a non-volatile solute of molar mass 40g/mol that should be dissolved in 114g of octane to lower its vapour pressure by 20% is:
The pressure imposed by a gas on a liquid (or solid) in a closed system at a certain temperature is... View Article
A bullet is fired from a gun, the force on the bullet is given by F=600−2×105t where F is in newton and t in second. The force on the bullet becomes zero as soon as it leaves the barrel. What is the average impulse imparted to a bullet?
Force acting on the bullet is given as ⇒ F=600−2×105t ⇒ t=600/2×105 t = 3×10−3s Now impulse imparted by the... View Article
A block of mass m = 1kg is placed on a smooth surface and is connected with a spring of constant K = 100N/m and another end of spring is connected to a fixed wall as shown. The block is pulled by a distance A = 0.10 m from its natural length and released at t = 0(A) The maximum speed is after t=π/20s (B) Time taken to cover the first 0.10 m, t=π/20s (C) Time taken to cover the first 0.05 m, t=π/40s (D) Time taken to cover the first 0.05 m, t=π/30s
Given parameters are K = 100N/m m = 1 kg L = 1 m Now, using the formula for the... View Article
A plane electromagnetic wave of frequency 25 MHz travels in free space along the x-direction. At a particular point in space and time, E=6.3 j^V/m. What is Bat this point?
The magnitude of the magnetic field will be given by the magnitude of the electric field divided by the speed... View Article
Consider the situation shown in figure. The wall is smooth but the surface of A and B in contact are rough. The friction on B due to A in equilibrium- (a) is upward (b) is downward (c) is zero (d) the system can’t remain in equilibrium
Here it is given that two blocks A and B who are attached together. From the figure we can see the... View Article
The magnetic induction at a point P which is 4cm distant from a long current carrying wire is 10 −3T. The field of induction at a distance 12 cm from the same current would be?
Magnetic induction, also called electromagnetic induction refers to the production of voltage (or EMF) across an electrical conductor placed inside... View Article
A body is thrown vertically upwards. Which one of the following graphs correctly represents the velocity vs time?
a) b) c) d) Velocity of a body thrown vertically upwards can be given as: vf= vi+ at where a=−g (always acts in downward... View Article
The maximum emission wavelength at temperature 2000K is 4μm. The maximum wavelength corresponding to temperature 2400K will be
Wien’s law or Wien’s displacement law, named after Wilhelm Wien was derived in the year 1893 which states that black... View Article
