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  1. The force on a current-carrying wire in a magnetic field is given by: F = BILsinθ The force is maximum when sinθ = 1, i.e., = 90° . This means the wire must be perpendicular to the magnetic field to experience the maximum force. Answer: (A) perpendicular to the magnetic field. For more visit here: hRead more

    The force on a current-carrying wire in a magnetic field is given by:
    F = BILsinθ

    The force is maximum when sinθ = 1, i.e., = 90°
    . This means the wire must be perpendicular to the magnetic field to experience the maximum force.
    Answer: (A) perpendicular to the magnetic field.

    For more visit here:
    https://www.tiwariacademy.com/ncert-solutions/class-12/physics/chapter-4/

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  2. To remove tension in the strings, the magnetic force must balance the gravitational force: Bil = mg Rearranging for current I: I = mg/BL Thus, the magnitude of current needed to make the net force zero is: I = mg/BL Answer: (C) mg/IB For more visit here: https://www.tiwariacademy.com/ncert-solutionsRead more

    To remove tension in the strings, the magnetic force must balance the gravitational force:
    Bil = mg
    Rearranging for current I:
    I = mg/BL
    Thus, the magnitude of current needed to make the net force zero is:
    I = mg/BL
    Answer: (C) mg/IB

    For more visit here:
    https://www.tiwariacademy.com/ncert-solutions/class-12/physics/chapter-4/

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  3. The voltage sensitivity of a galvanometer is given by: Voltage Sensitivity = Current Sensitivity/R If current sensitivity increases by 20% and resistance increases by 25%, the net change in voltage sensitivity is: 1.2/1.25 = 0.96 This indicates a 4% decrease in voltage sensitivity. Answer: (D) DecreRead more

    The voltage sensitivity of a galvanometer is given by:
    Voltage Sensitivity = Current Sensitivity/R
    If current sensitivity increases by 20% and resistance increases by 25%, the net change in voltage sensitivity is:
    1.2/1.25 = 0.96
    This indicates a 4% decrease in voltage sensitivity.
    Answer: (D) Decrease by 4%.

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    https://www.tiwariacademy.com/ncert-solutions/class-12/physics/chapter-4/

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  4. The magnetic field around a long, straight current-carrying wire is given by: B = μ0I/2πr ​Substituting values: B = 4π × 10⁻⁷ × 5/2π × 0.10 = 1 × 10⁻⁵ T Using the right-hand thumb rule, the magnetic field at a point due south acts upward. Therefore, the correct answer is: (B) 1 × 10⁻⁵ T acting upwarRead more

    The magnetic field around a long, straight current-carrying wire is given by:

    B = μ0I/2πr

    ​Substituting values:
    B = 4π × 10⁻⁷ × 5/2π × 0.10 = 1 × 10⁻⁵ T
    Using the right-hand thumb rule, the magnetic field at a point due south acts upward. Therefore, the correct answer is:
    (B) 1 × 10⁻⁵ T acting upwards.

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    https://www.tiwariacademy.com/ncert-solutions/class-12/physics/chapter-4/

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  5. An α-particle projected along the Y-axis with velocity v in the presence of uniform electric and magnetic fields along the X-axis experiences a magnetic force perpendicular to both velocity and magnetic field, causing circular motion in the YZ plane. The electric field imparts acceleration along theRead more

    An α-particle projected along the Y-axis with velocity
    v in the presence of uniform electric and magnetic fields along the X-axis experiences a magnetic force perpendicular to both velocity and magnetic field, causing circular motion in the YZ plane. The electric field imparts acceleration along the X-axis, resulting in a helical trajectory with its axis parallel to the X-axis.
    Answer: (C) Helical with its axis parallel to X-axis.

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    https://www.tiwariacademy.com/ncert-solutions/class-12/physics/chapter-4/

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