Through how many volts of potential difference must an electron, initially at rest, be accelerated to achieve a wave length of 0.27nm? a) 4.6 v
b) 0.046 v
c) 0.27 v
d) 4.6 mv
e)4.6 kv

20.7 volts

Explanation:

m = mass of electron = 9.1 x 10⁻³¹ kg

λ = wavelength of electron = 0.27 x 10⁻⁹ m

v = speed of electron

Using de-broglie's hypothesis

λ m v = h

(0.27 x 10⁻⁹) (9.1 x 10⁻³¹) v = 6.63 x 10⁻³⁴

v = 2.7 x 10⁶ m/s

ΔV = Potential difference through which electron is accelerated

q = charge on electron = 1.6 x 10⁻¹⁹ C

Using conservation of energy

(0.5) m v² = q ΔV

(0.5) (9.1 x 10⁻³¹) (2.7 x 10⁶)² = (1.6 x 10⁻¹⁹) ΔV

ΔV = 20.7 volts

a small object of mass 3.66 g and charge -17.6 µc is suspended motionless above the ground when immersed in a uniform electric field perpendicular to the ground. what are the magnitude and direction of the electric field?

no. dot product   =0 when vecs at right angles