When blue light (450 nm) is shone on a particular metal surface, electrons are ejected with a kinetic energy of 2.5 x 10-20 J. Calculate the work function for this metal.

the work function of the metal is 4.167 x 10⁻¹⁹ J .

Explanation:

Given;

wavelength of the incident light, λ = 450 nm = 450 x 10⁻⁹ m

kinetic energy, K.E = 2.5 x 10⁻²⁰ J

The energy of the incident light is calculated as;

Apply Einstein photoelectric equation to determine the work function of the metal;

E = W + K.E

where;

W is the work function of the metal

W = E - K.E

W = 4.417 x 10⁻¹⁹ J - 2.5 x 10⁻²⁰ J

W = 44.17 x 10⁻²⁰ J -  2.5 x 10⁻²⁰ J

W = 41.67 x 10⁻²⁰ J

W = 4.167 x 10⁻¹⁹ J

Therefore, the work function of the metal is 4.167 x 10⁻¹⁹ J .

answer: 802.3 kilo joules of energy represents 191.75 kilo calorie of energy.

explanation:

energy released during combustion of one mole methane = 802.3 kilo joules

if 1 kilo joule = 0.239006   kilo calorie

then ,802.3 kilo joule will be = 802.30.239006 kilo calorie

802.3 kilo joule = 191.75 kilo calorie

hence, the energy in kilo calorie is 191.75 kilo calorie.

laticia draws the diagram below to show earth’s magnetic field.

answer

the arrows to the right of earth should point up.