Answer:
Temperature on the inside ofthe box
Explanation:
The power of the light bulb is the rate of heat conduction of the bulb, 
The thickness of the wall, L = 1.2 cm = 0.012m
Length of the cube's side, x = 20cm = 0.2 m
The area of the cubical box, A = 6x²
A = 6 * 0.2² = 6 * 0.04
A = 0.24 m²
Temperature of the surrounding, 
Temperature of the inside of the box, 
Coefficient of thermal conductivity, k = 0.8 W/m-K
The formula for the rate of heat conduction is given by:
Answer:
mass of the air = 14.62kg
Workdone = 415.88 kJ
Heat transfer = 415.88 kJ
Explanation:
Please find the attached files for the solution
Answer:
Method B is the more efficient way of heating the water.
Explanation:
Method B is more efficient because by placing a heating element in the water as in described in method B, the heat that is lost to the surroundings is minimized which implies that more heat is supplied directly to the water. Therefore, more heating is achieved with a lesser amount of electrical energy input. Whereas placing the pan on a range means more heat losses to the surrounding and as such it will take a longer time for the water to heat up and also take more electrical energy.
Answer:
A. N type impurities
B. P type impurities
Explanation:
A. The impurities contribute free electrons and changing the conducting property of the semi conductor. When a pentavalent impurities in a semi conductor( impurities with five valence electron) , the impurity atom replace some of the semi conductor atoms in the crystal structure where 4 of the valence electron would be involved in bonding of 4 neighbouring semiconductor while leaving the fifth electron to be free(negative charge carrier) which is available for detachment.
B. When a trivalence impurity is added to semiconductor, instead of excess electron, there will be excess hole created by crystals. Reason for this attribute is the trivalence atom will replace some tetra valence semiconductor atom, when three valence electrons of the 3 valence electrons of the trivalent impurity atom make bond with three neighbouring semiconductor which gives rise to lack of electron in the bond of the fourth neighbouring semiconductor which contribute a whole to the crystalline since trivalent impurity contribute excess holes to the crystal of semi conductor, this holes can accept electrons.
