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A galvanometer of resistance 25 Ω is connected to a battery of 2 volt along with a resistance in series. When the value of this resistance is 3000 Ω, a full scale deflection of 30 units is obtained in the galvanometer. In order to reduce this deflection to 20 units, the resistance in series will be
Given: Galvanometer resistance (G) = 25 Ω Battery voltage (V) = 2 V Initial series resistance (R) = 3000 Ω Full-scale deflection = 30 units New deflection = 20 units The current sensitivity is proportional to deflection: I₂/I₁ = 20/30 = 2/3 Current through the circuit: I₁ = V/G+R = 2/3000+25 New resRead more
Given:
Galvanometer resistance (G) = 25 Ω
Battery voltage (V) = 2 V
Initial series resistance (R) = 3000 Ω
Full-scale deflection = 30 units
New deflection = 20 units
The current sensitivity is proportional to deflection:
I₂/I₁ = 20/30 = 2/3
Current through the circuit:
I₁ = V/G+R = 2/3000+25
New resistance:
I₂ = 2/G+R’
2/3/1 = G+R/G+R’
R’ = 4514Ω
Answer: (A) 4514 Ω
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A conducting wire of length l is turned In the form of a circular coil and a current l is passed through it. For the torque, due to magnetic field produced at its centre, to be maximum, the number of turns in the coil will be
The torque (τ) on a current-carrying coil is given by: τ = nI AB For fixed wire length l, the radius is: r = l/2πn Torque is maximized when n = 2, as the product of the number of turns and area is optimized. Answer: (B) Two For more visit here: https://www.tiwariacademy.com/ncert-solutions/class-12/Read more
The torque (τ) on a current-carrying coil is given by:
τ = nI AB
For fixed wire length l, the radius is:
r = l/2πn
Torque is maximized when n = 2, as the product of the number of turns and area is optimized.
Answer: (B) Two
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The gyro-magnetic ratio of an electron in an H-atom, according to Bohr model, is
The gyro-magnetic ratio (γ) of an electron in a hydrogen atom, according to the Bohr model, is given by: γ = e/2m It is independent of the orbit number (n) as it only depends on fundamental constants (e and m). The ratio is negative because the electron has a negative charge. Answer: (B) Negative htRead more
The gyro-magnetic ratio (γ) of an electron in a hydrogen atom, according to the Bohr model, is given by:
γ = e/2m
It is independent of the orbit number (n) as it only depends on fundamental constants (e and m). The ratio is negative because the electron has a negative charge.
Answer: (B) Negative
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See lessTwo wires of same length are shaped into a squatr and a circle if they carry same current, ratio of magnetic moment is :
Let the length of each wire be L. For a square of side a, 4a = L ⟹ a = L/4. Magnetic moment, M₁ = IA² = I L/4 ². For a circle of radius r, 2πr = L ⟹ r = L/2π. Magnetic moment, M₂ =Iπr² = Iπ L/2π ² . Ration. M₁/M₂ = 2/π. Answer: (A) 2 : π For more visit here: https://www.tiwariacademy.com/ncert-solutRead more
Let the length of each wire be L.
For a square of side a, 4a = L ⟹ a = L/4. Magnetic moment,
M₁ = IA² = I L/4 ².
For a circle of radius r, 2πr = L ⟹ r = L/2π. Magnetic moment,
M₂ =Iπr² = Iπ L/2π ² .
Ration. M₁/M₂ = 2/π.
Answer: (A) 2 : π
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Current sensitivity of a galvanometer can be increased by decreasing:
Current sensitivity of a galvanometer is given by S = nBA/K where n = number of turns, B = magnetic field, A = area of coil and k = torsional constant. To increase sensitivity, S should be maximized. Decreasing the torsional constant k increases S as they are inversely proportional. Hence, the correRead more
Current sensitivity of a galvanometer is given by
S = nBA/K
where n = number of turns, B = magnetic field, A = area of coil and k = torsional constant.
To increase sensitivity, S should be maximized. Decreasing the torsional constant
k increases S as they are inversely proportional.
Hence, the correct answer is (C) Torsional constant k.
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