Answer:
option B
Explanation:
we know,
Force between two charge is calculated by

r is the distance between the two charges
k is Coulomb constant.
give two small object with charge Q
now, Force
......(1)
now,
New force if another charge is equal to 4 Q


now from equation 1

Hence, the correct answer is option B
here the charge density of metal plate is given as

now the electric field is given Gauss law

now here E = constant
so we will have

Since total area on both sides of plate will be double and becomes 2A



Now if we will find the electric field inside the metal plate
Then as we know that total charge inside the plate will always be zero
so we have

Answer:
Explanation:
Since the surface is frictionless therefore there will be no friction force on block but there will be weight of block which we can divide in to two components i.e. mgcosθ &mgsinθ which is perpendicular and parallel to the surface respectively.
In response to mgcosθ ramp will apply a normal force to the block which will be of equal magnitude to that of mgcosθ.
Therefore Ramp will apply a Force of mgcosθ on block where m is the mass of block.
Answer:
Δt = 5.29 x 10⁻⁴ s = 0.529 ms
Explanation:
The simple formula of the distance covered in uniform motion can be used to find the interval between when the sound arrives at the right ear and the sound arrives at the left ear.

where,
Δt = required time interval = ?
Δs = distance between ears = 18 cm = 0.18 m
v = speed of sound = 340 m/s
Therefore,

<u>Δt = 5.29 x 10⁻⁴ s = 0.529 ms</u>
An ice cube would transfer heat to another object whose temperature
is lower than zero°C (32°F).
A block of "dry ice" is sitting there at a temperature of -78°C (-109°F).
An ice cube helps to melt dry ice nice and fast.
If you could find a block of solid nitrogen, its temperature would be
63K (-210°C, -346°F). An ice cube would transfer heat to that baby
so fast that it would instantly boil.