Red light is used as danger signal because it is:
- AAccepted as symbol
- BPleasing to the eye
- CSensitive to the eye
- DHas high wavelength
Red light is used as danger signal because it is:
Explanation:
Red light is used as danger signal because it is having high wavelength, less scattering ,hence can travel larger distances.
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
The earth’s magnetic field at a given point is 0.5
. This field is to be annulled by magnetic induction at the center of a circular conducting loop of radius 5.0cm. The current required to be flown in the loop is nearly
|
(a) 0.2 A |
(b) 0.4A |
(c) 4A |
(d) 40A |
Two straight long conductors AOB and COD are perpendicular to each other and carry currents
and
. The magnitude of the magnetic induction at a point P at a distance a from the point O in a direction perpendicular to the plane ACBD is
|
(a) |
(b) |
(c) |
(d) |
The work function of a substance is 4.0 eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately
|
(a) 540 nm |
(b) 400 nm |
(c) 310 nm |
(d) 220 nm |
Four capacitors of each of capacity 3μF are connected as shown in the adjoining figure. The ratio of equivalent capacitance between A and B and between A and C will be
|
(a) 4 : 3 |
(b) 3 : 4 |
(c) 2 : 3 |
(d) 3 : 2 |
A parallel plate capacitor of area A, plate separation d and capacitance C is filled with three different dielectric materials having dielectric constants and
as shown. If a single dielectric material is to be used to have the same capacitance C in this capacitor, then its dielectric constant k is given by
|
(a) |
(b) |
|
(c) k = |
(d) |
Thomson coefficient of a conductor is 10μV/K. The two ends of it are kept at 50℃ and 60℃ respectively. Amount of heat absorbed by the conductor when a charge of 10C flows through it is
|
(a) 1000 J |
(b) 100 J |
(c) 100 mJ |
(d) 1 mJ |
An AM wave has 1800 watt of total power content, For 100% modulation the carrier should have power content equal to
|
(a) 1000 watt |
(b) 1200 watt |
(c) 1500 watt |
(d) 1600 watt |
Consider the following two statements A and B and identify the correct choice given in the answers
(A) Duddells thermo-galvanometer is suitable to measure direct current only
(B) Thermopile can measure temperature differences of the order of ![]()
|
(a) Both A and B are true |
(b) Both A and B are false |
|
(c) A is true but B is false |
(d) A is false but B is true |