The hall effect can be used to calculate the charge-carrier number density in a conductor. a conductor carrying current of 2.0 a is 0.50 mm thick, and the hall voltage is 4.5 x 10 v when it is in a uniform magnetic field of 1.2 t. what is the density of charge carriers in the conductor? a) n = 4.6 x 1027 charges/m b) n = 1.7 x 1027 charges/m c) n = 1.0 x 1028 charges/m? d) n = 6.7 x 1027 charges/m?

The density of charge carriers in the conductor is

(d) is correct option.

Explanation:

Given that,

Current = 2.0 A

Thickness = 0.50 mm

Hall voltage

Magnetic field = 1.2 T

We need to calculate the density of charge carriers in the conductor

Using formula of the density of charge

Where, i = current

B = magnetic filed

V = voltage

L = thickness

Put the value into the formula

Hence, The density of charge carriers in the conductor is

you can look at magnesium, it can react with oxygen to form oxides. (chemical) it is malleable and a solid at room temperature. (physical)

to measure its density, the mass and volume can be worked out and from this density too. look up the equation, it is quite easy :) 
physical changes -- it can be melted, and oxidized 

the chemical changes of oxidation magnesium looses electrons to form oxides, this is a chemical reaction- chemical change..--- use to get the density use (rho) or density D = M/V