Answer:

Explanation:
The relationship between the refractive index and the critical angle is given as follows:

where,
η = refractive index = 1.67
θc = critical angle =?
Therefore,


Answer:
current going into a junction in a circuit is EQUAL TO the current comming out of the junction.
Explanation:
Krichhoff's Current Law
Kirchhoff's current law (1st Law) states that current flowing into a node (or a junction) must be equal to current flowing out of it.
Answer:
0.0321 g
Explanation:
Let helium specific heat 
Assuming no energy is lost in the process, by the law of energy conservation we can state that the 20J work done is from the heat transfer to heat it up from 273K to 393K, which is a difference of ΔT = 393 - 273 = 120 K. We have the following heat transfer equation:

where
is the mass of helium, which we are looking for:

Answer:
884 balloons
Explanation:
Assume ideal gas, since temperature is constant, then the product of pressure and volume is constant.
So if pressures reduces from 100 to 1.2, the new volume would be

The spherical volume of each of the balloon of 30cm diameter (15 cm or 0.15 m in radius) is

The number of balloons that 12.5 m3 can fill in is

Answer:
A hypothesis is what you think will happen.
A conclusion is the results of an experiment summarized.
Hope this helps.