Answer:
<em>1.187 x 10^8 m/s</em>
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Explanation:
the potential of the electric field V = 40 kV = 40000 V
the charge on an electron e = 1.6 x 10^-19 C
The energy of an accelerated electron in an electric field is given as
E = eV
E = 1.6 x 10^-19 x 40000 = 6.4 x 10^-15 J
This energy is equal to the kinetic energy with which the electron moves, according to the conservation of energy.
The kinetic energy = 
where
m is the mass of the electron = 9.109 x 10^-31
v is the speed of the electron.
Equating the energy, we have
6.4 x 10^-15 = 
6.4 x 10^-15 = 4.55 x 10^-31 
= 1.41 x 10^16
= <em>1.187 x 10^8 m/s</em>
Answer:
Explanation:
Magnetic field due to circular wire at the center = μ₀ I / 2 r
I is current and r is radius . μ₀ = 4π x 10⁻⁷.
field B₁ due to inner loop
B₁ = 4π x 10⁻⁷ x 12 / 2 x .20
= 376.8 x 10⁻⁷
Field due to outer loop
B₂ = 4π x 10⁻⁷ x I / 2 x .30
For equilibrium
B₁ = B₂
376.8 x 10⁻⁷ = 4π x 10⁻⁷ x I / 2 x .30
I = 18 A.
The direction should be opposite to that in the inner wire . It should be anti-clockwise.
Answer:
The flashlight leaves the water at an angle of 51.77°.
Explanation:
if n1 = 1.33 is the refractive index of water and ∅1 is the angle at which the flashlight shine beneath the water, and n2 = 1.0 is the refractive index of air and ∅2 is the angle the flashlight leaves the water.
Then, according to Snell's law :
n1×sin(∅1) = n2×sin(∅2)
sin(∅2) = n1×sin(∅1)/n2
= (1.33)×sin(36.2)/(1.0)
= 0.7855055×379
∅2 = 51.77°
Therefore, the flashlight leaves the water at an angle of 51.77°.
In Burglar alarm, LDR acts an AND gate.
Answer: C
Explanation
The LDR is light dependent resistor. The principle used in the working of LDR is that the resistance is inversely proportional to the intensity of light falling on the diode.
In burglar alarm, LDR diode is combined with an IC 555.
Normally an LED source is made to be incident on the LDR diode with same intensity such that the resistance will be maintained constant.
As the LDR is connected with IC, the voltage will be high when light is falling on the diode.
The IC will give only two output states that is high and low. This confirms that LDR in burglar alarm act as AND gate.
As the thief enters and crosses the LED light, the intensity of the light falling on the diode will decrease leading to decrease in the voltage which will cause the alarm to beep.
Answer:
34.3 m/s
Explanation:
Newton's Second Law states that the resultant of the forces acting on the car is equal to the product between the mass of the car, m, and the centripetal acceleration 
(because the car is moving of circular motion). So at the top of the hill the equation of the forces is:
where
(mg) is the weight of the car (downward), with m being the car's mass and g=9.8 m/s^2 is the acceleration due to gravity
R is the normal reaction exerted by the road on the car (upward, so with negative sign)
v is the speed of the car
r = 0.120 km = 120 m is the radius of the curve
The problem is asking for the speed that the car would have when it tires just barely lose contact with the road: this means requiring that the normal reaction is zero, R=0. Substituting into the equation and solving for v, we find:
