Magnetic Effects of Electric Current — Science STD 10 — Question

What do you understand by a mixed combination of resistances?

The speed of light in water is 2.25 × 10⁸ m/s. If the speed of light in vacuum be 3 × 10⁸m/s, calculate the refractive index of water.

With the help of a ray diagram explain why a concave lens diverges the rays of a parallel beam of light.

State and define the S.I. unit of power of a lens.

It is desired to obtain an erect image of an object, using concave mirror of focal length of 12cm.
Where will the image of this object be, if it is placed 24cm in front of the mirror? Draw ray diagram for this situation also to justify your answer.
Show the positions of pole, principal focus and the centre of curvature in the above ray diagrams.

While studying the dependence of potential difference (V) across a resistor on the current (I) passing through it, in order to determine the resistance of the resistor, a student took 5 readings for different values of current and plotted a graph between V and I. He got a straight line graph passing through the origin. What does the straight line signify? Write the method of determining the resistance of the resister using this graph.

How it can be proved that the basic structure of the modern periodic table is based on the electronic configuration of atoms of different elements?

Why are the ‘danger signal’ lights red in colour?

How is the reflection of light ray from a plane mirror different from the refraction of light ray as it enters a block of glass?

What is an electric circuit? Distinguish between an open and a closed circuit.