Which of the following statements is correct about the effect of the presence of a third charge on Coulomb force between the two charges?

A polythene piece rubbed with wool is found to have a negative charge of \( 8 \times 10^{-10} \, \text{C} \). What is the number of electrons transferred ?

A point charge is kept at the centre of a metallic insulated spherical shell. Then :

You are given a transformer that has 800 turns on its primary coil and 64 turns on its secondary coil. A voltage of 220 V is applied to the primary coil. What is the output voltage?

Given that two identical coils, one of copper and another of aluminium are rotated with the same angular speed in an external magnetic field, which of the following statements is true?

Which of the following is correct for a parallel plate capacitor of separation 'd' when a slab of material of dielectric constant \(k\) has the same area as the plate of capacitor but has a thickness \(d / 2\) is inserted between the plates?
A. Its capacitance decreases
B. Its capacitance increases
C. \(C=C_0\left(\frac{2 k}{k+1}\right)\)
D. \(C=C_0\left(\frac{k+1}{2 k}\right)\)
E. Charge remains same.
Choose the correct answer from the options given below:

A bulb of \( 100 \text{ W} \) glows for \( 6 \text{ hours} \) a day. The units of energy consumed in \( 7 \text{ days} \) would be :

Read the passage carefully and answer the questions
Carbohydrates such as cane sugar, glucose, starch etc. belong to a class of naturally occurring organic compounds. Structurally these are polyhydroxy aldehydes or ketones or the compounds which produce such units on hydrolysis. Carbohydrates which are sweet in taste are called sugars. Theses sugars can be reducing or non-reducing. Monosaccharides cannot be hydrolyzed to simpler units whereas Oligosaccharides yield two to ten monosaccharide units on hydrolysis. Polysaccharides yield large number of monosaccharide units on hydrolysis. This class of biomolecules is essential for living systems as they serve as storage molecules in plants and animals. In addition, they provide raw materials for important industries like furniture, textiles, paper, lacquers and breweries. Two aldopentose form important constituents of nucleic acids. Carbohydrates are also called saccharides (Greek: sakcharon which means sugar). Sugar which is used in household and in milk also comes under this class of biomolecules.
Reducing sugars respond to

A solenoid with 100 turns per metre carries a current of 1.2 A. The magnetic intensity inside the solenoid is :

The sides of an equilateral triangle are increasing at the rate of \(2 cm / sec\). The rate at which the area increases when the side is 10 cm , is

Identify the incorrect statement about the genetic modification.

The organisation set up by the Indian Government to take decisions regarding the validity of GM research and the safety of introducing GM-organism is:

A wire carries a current of 2.0 A. The number of electrons crossing through its cross-section in 10 s will be