Answer:
156.3 J
Explanation:
E = Amplitude of the electric field = 25000 V/m
t = time interval = 1 minute = 60 sec
d = diameter of the spot = 2 mm = 2 x 10⁻³ m
Area of the spot is given as
A = (0.25) πd²
A = (0.25) (3.14) (2 x 10⁻³)²
A = 3.14 x 10⁻⁶ m²
Energy delivered to the spot is given as
U = (0.5)ε₀ E² c A t
Inserting the values
U = (0.5) (8.85 x 10⁻¹²) (25000)² (3 x 10⁸) (3.14 x 10⁻⁶) (60)
U = 156.3 J
