Physics - Online Test
Q1. If a positive charge moves opposite to the direction of the electric field
Answer : Option D
Explaination / Solution:
A positive charge experiences a force in the direction of the field. If it moves opposite to the direction of the field, negative work is done by the electric field on the charge. Potential energy of the charge increases since an external source is required to do work on the charge against the direction of the field, and the work done is stored in the charge as its potential energy.
Q2. The units of pressure in SI system is
Answer : Option D
Explaination / Solution:
The SI unit for pressure is the pascal (Pa), equal to one newton per square metre (N/m2, or kg. m. s−2). This name for the unit was added in 1971; before that, pressure in SI was expressed simply in newtons per square metre
Q3. The order of inter atomic distance in liquids is about
Answer : Option C
Explaination / Solution:
Using the assumption of little spheres (for interatomic space) the spacing between the molecules at about 2X10-10 m i.e.
The size of an atom is about an angstrom (10 -10 m) . In solids, which are tightly packed, atoms are spaced about a few angstroms (2 Å) apart.
Q4. According to Snell’s law
Answer : Option A
Explaination / Solution:
No Explaination.
Q5. Contains
Answer : Option A
Explaination / Solution:
Number of protons = Atomic number = 79
Number of neutrons = Atomic mass number - atomic number = 197-79 = 118.
Q6. correct expression for force on a current carrying conductor of length dl in a magnetic field is
Answer : Option B
Explaination / Solution:
force experienced by a conductor of length l carrying current I placed in magnetic field B is given by .Here =
Q7. Plots of pressure as a function of temperature for gas thermometers containing different types and quantities of gas converge to the same point when extrapolated to zero pressure. The temperature value to which converge is.
Answer : Option B
Explaination / Solution:
Absolute zero temp. = 0K
Q8. Joule is the SI unit of
Answer : Option D
Explaination / Solution:
The joule (symbol J), is a derived unit of energy in the International System of Units. It is equal to the energy transferred to (or work done on) an object when a force of one newton acts on that object in the direction of its motion through a distance of one metre (1 newton metre or N⋅m).
Q9. The sensitivity of the potentiometer can be increased by:
Answer : Option A
Explaination / Solution:
A potentiometer is considered to be sensitive if the potential gradient is low. Such a potentiometer can measure very small changes in potential difference. Increasing the length of the potentiometer wire decreases the potential gradient. Its sensitivity increases. Increasing potential gradient decreases the sensitivity. increasing the emf of the primary cell and by decreasing the length, potential gradient increases.
Q10. Any periodic function can be expressed as superposition of-
Answer : Option D
Explaination / Solution:
Because sine and cosine functions both are periodic in nature and according to Fourier theorem a" Fourier series" is a way to represent a function as the sum of simple sine waves. More formally, it decomposes any periodic function or periodic signal into the sum of a (possibly infinite) set of simple oscillating functions, namely sines and cosines, or in simple terms any periodic function can be expressed as sum or superposition of sine and cosine functions with fixed time periods.
