The unification of electromagnetism and optics leads to the:
A
Celestial and terrestrial mechanics.
B
Discovery of uncertainity principle.
C
Discovery of optical fibres.
✓
Discovery of light as an electromagnetic wave.
Answer
Correct option: D.
Discovery of light as an electromagnetic wave.
In $1873,$ James Clerk Maxwell showed that the unification of electromagnetism and optics leads to the discovery of light as an electromagnetic wave.
Weak nuclear forces appears only between elementary particles involved in nuclear processes of radioactivity. Thus, it operates among some elementary particles, particularly electrons and neutrino.
However, gravitational force operates among all objects in universe and electromagnetic force operates among charged particles.
Which of the following statement regarding 'Prahar' missile developed by $\text{DRDO}$ and test fired in the month of July, $2011$ are correct?
$1.$ It is a single stage missile.
$2.$ Its striking range is $500\ km.$
$3.$ It is fueld by solid propellants.
$4.$ Several ‘Prahar' missiles can be fired in one salvo.
Select the correct answer using the code given below:
Marie Curie had discovered radium and polonium, whereas spontaneous radioactivity was discovered by Bequerrel, Bohr discovered quantum model of hydrogen atom and Max Planck discovered quantum theory of radiation.
The mass of air inside a room of dimension $(3 \times 4 \times 6)m^3$ can be compared to the mass of:
A
Hen.
B
Pencil.
✓
Table.
D
Truck. Choose the correct option. $($Given density of air $= 1.3\ kgm^{-3})$
Answer
Correct option: C.
Table.
Mass of air in the room
$= 3 \times 4 \times 6 \times 1.3\ kg$
$= 93.6\ kg$
$[\because$ Volume of the room $= 3 \times 4 \times 6m^3]$
Which is approximately equal to the mass of table.
So, correct option is $(c).$
Conservation laws are basically hypothesis, based on observations and experiments. Thus, these laws cannot be proved but can be verified or disproved by experiments.
A chemical reaction is basically a re$-$arrangement of atoms among different molecules.
When there is change in bond energy or binding energy, the balance energy may be absorbed or released.
So, energy evolved in a chemical reaction comes from bond energy.
According to law of conservation of energy and momentum for $\beta-$decay, the existence of a new particle along with electron was predicted which was called:
A
Electron.
B
Proton.
C
Neutron.
✓
Neutrino.
Answer
Correct option: D.
Neutrino.
Using the conservation laws of energy and momentum for $B-$decay. Wolfgang Pauli $(1900-1958)$ correctly predicted in $1931$ the existence of a new particle called neutrino emitted in $B-$decay along with the electron.