Physics 2

Question 1

What is the difference between static and dynamic equibrilium?

How do you solve such problems?

Answer 1

Static equibrilium = objects are at rest

Dynamic equibrilium = constant velocity, acceleration is 0

Add ma or Fl(mgl) to loosing side of equation

Question 2

What is Torque?

What the is formula?

Answer 2

Torque is the ability of an object to rotate something, the further away the less force is required

T = F*L

T = mgL

Question 3

What is work?

What are the different equations?

Answer 3

Work is the change in enery of an object, it might be potential, kinetic, heat, spring etc

Then think of work as :

W = F.d.CosØ

Question 4

How do Machines Work?

Explain using Ramp, Pulley and Lifts

Answer 4

Machines change the force required to do the work by increasing the distance. They do not change the amount of work required.

Ramp : F.d = F.d

Pulley : F = mg/# of verticle ropes connected

Lifts : P = P

F₁A₂=F₂A₁ (F₂ can be mg)

Question 5

What is Power?

Answer 5

Power is

• Change in Energy/time
• Work/time
• FdCosØ/time
• FvCosØ

Question 6

What is the charge on an electron?

Answer 6

e = 1.6 * 10^-19 C

Question 7

What is an electric field?

What are field lines?

What are equipotential lines?

What is a dipole?

Answer 7

Field : An invisible forces acting on a mass or charge

Field Lines : +ve to -ve. Closer lines = stronger field

Equipotential Lines : Points of equal potential

Dipole : Seperation of +ve and -ve charges of equal magnitude. Align to magnetic field or it has PE

Question 8

F = mg

F = G m₁m₂/r²

g = G m_e/ r_e²

g = F/m

PE = mgh

PE = -G m₁m₂/ r

V = gh

V = G m/ r

Answer 8

F = q E

F = K q₁ q₂ / d²

E = K q /d^₂

E = F / q

PE = qEd

PE = (-/+) K q₁ q₂ / d

V = Ed

V = K q / d

Question 9

How is a magnetic field created?

What is the equation for the Force of a magnetic field?

What is the Right Hand Rule?

Answer 9

A changing electric field creates a magnetic field.

F = qvB SinØ

RHR : v(thumb), B(finger), F(2nd finger)

We be fucking

Used for +ve particle

Use Left hand for -ve particle

(x) in (.) out

Question 10

What is current?

What is Voltage?

What is Resistance?

Answer 10

Current : Flow of electrons

Voltage : Amount of PE per unit charge or amount of work required to move a charge against an electric field

V = PE / q

Resistance : Like drag or friction

R = p L/A

p = resistivity of substance

Question 11

What is Ohm’s law?

What things effect Capacatince?

Answer 11

V = I R

Q = C V

PE = (1/2) CV²

1. Dielectric strength
2. Surface Area of Capacitor

Question 12

What is Power?

Difference between AC and DC?

Answer 12

P = I V

AC = average = 0 so we take RMS value

Polarity keeps on changing

Question 13

What does intensity depend on?

How is attentuation calculated?

How does the decible system work?

Answer 13

I is proportional to A² and f²

Att= 4πr²

Decible System : 10 * log (I/I_o)

Question 14

What are transverse, longitudinal, electromagnetic and mechanical waves?

How do you calculate the velocity of a wave? Light and sounds?

How are beats calculated?

Answer 14

Transverse : Displace medium perpendicular to direction of travel

Longitudinal : Displace medium parallel to direction of travel

Electromagnetic : Don’t require medium to travel

Mechanical : Require medium to travel

V = Â(wavelength) f

V = Â / t

Frequency doen’t change in medium

Light = travel slower in solids

Sounds = v = sqrt (stiff/density) Faster in solids

F_beat = f₁-f₂

Question 15

How does the doppler effect work?

Answer 15

Anything coming towards us has a higher frequency and anything going away has a lower frequency

delta f / f_s = v(relative) / c(wave speed)

Question 16

What is the wavelength of 1st, 2nd and 3rd harmonic of a closed and open system?

Answer 16

Closed:

wavelength₁=2L

wavelength₂=L

wavelength₃=2L/3

Open:

wavelength1=4L

wavelength2=4L/3

wavelength3=4L/5

f = v/wavelength

Question 17

How does f and wavelength change?

How is light a particle?

How is light a wave?

Answer 17

inc f = inc energy = dec wavelenth

KE = hf - work function

x = wavelenth L/d

Question 18

What is index of refraction?

What is snells law?

What is diffraction and dispersion?

When does total internal refraction happen?

Answer 18

Index of refraction : n = c/v , it tells us the speed of light in that medium as compared to air

Snell’s law : n₁SinØ=n₂SinØ

Diffraction : Wave stuff

Dispersion : V bends the most, R bends the least

Total internal refraction when Ø=90

Question 19

What are the types of images formed in convex and concave lens?

What happens in mirrors?

Answer 19

Convex : between infinity and f = RIP

between f and lens = VUN

Concave = VUN

Mirrors work opposide :

Concave mirror = convering lens

Convex mirror = diverging lens

Plane = VUN image equidistant

Question 20

What are the 3 equations for lens?

What are the caveats?

Answer 20

f=r/2

(1/f)=(1/d_i)+(1/d_o)

M = -d_i/d_o =h_i/h_o

Do is always +ve

f for convex lens is always +ve

-M means inverted image

Question 21

What is the difference and how are they cured?

Power and 2 lens systems?

Answer 21

Near Signtness : Image formed infront of retina, diverging concave lens required

Far Signtness : Image formed behind retina, converging convex lens required

Power = 1/f

M= m₁ * m₂