Practice question

Given: An electron moves with a speed of 2 × 10⁶ m/s perpendicular to a magnetic field of 0.7 T . What is the radius of its path? (Mass = 9.1 × 10⁻³¹ kg, charge = 1.6 × 10⁻¹⁹ C ) These values define the system as per NCERT data. Formula: Radius r = mv/qB. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: r = frac9.1 × 10⁻³¹ × 2 × 10⁶¹.6 × 10⁻¹⁹ × 0.7 = frac1.82 × 10⁻²⁴¹.12 × 10⁻¹⁹= 1.625 × 10⁻⁵ m = 1.625 × 10⁻³ cm . Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.