Skip to main content


Showing posts from December, 2016

Three sum of electrical power have been discussed. Here. These sum will give a basic idea of finding electrical power and electrical energy consumed by a load or electrical energy supplied by a source like battery.
The sums are:
1. Two resisters of value 6 ohm and 12 ohms are connected in series across a battery of 12 volt. Draw the circuit diagram and calculate.
a) Current flowing through each resistor.
b) The electrical energy consumed by each resistor.
+ Sollution- Close the Sollution 2. These two resistors again connected in parallel and the above data are again calculated.
+ Sollution- Close the Sollution 3. Two bulb L1 and L2 of rating 100 W 200 V and 10 W 200 Volt respectively are connected across a supply of 200 V in series. Find
a) Current flowing through each bulb
b) which bulb will consume more power.

There are two laws of refraction of light. these are :
a) Incident say , refracted ray and normal lie on same plane .
The concept of plane is shown in the image. In terms of x,y and z co-ordinate system , the y-z plane is shown in light sky blue colour. We write on our copy which is considered x-y plane. The image is given just for understanding of plane concept. It is not needed while writing the law. Try to image other planes in the image.
b) Ratio of sin of angle of incidence and sine of angle of refraction remains constant for a pair of media. i.e. sin i / sin r = constant (n)
this constant is called refractive index of medium 2 with respect to medium 1.
or we can write
n2 / n 1 = sin i / sin r
Where n 1 is the refractive index of first medium here air. And n2 is the refractive index of second medium here glass.
∴ n2 = n1 x ( sin i / sin r )
If you have any query regarding the laws of refraction then comment below.

Featured Post

Ratio Mathematics ICSE Tutorial Class 7

There are four videos of Ratio class 7. Few sums have also been explained with very easy steps. If there are any doubts then comment below. We will try to clear those doubts.

1. Understanding Ratio:

2. Comparing Ratio Basic and Shortcut method:

3. Compound Ratio , continued Ratio Dividing a number in a given Ratio:

4. Solution of few problem of ratio:
These sums of Ratio class 7 have been discussed in this video:
1. write in simplest form
72:108, 1/6:1/2,
15cm to 4m.
2. Population of a village is 32400. The ratio of literate
to illiterate person in the village is 11:7. Find the actual number of literate person and illiterate person. .
3. If a, b and c are three numbers such that a:b=4:9 and b:c=27:35. Find a:c
4. In what ratio should we increase 650 to obtain 1000.