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Test your basic knowledge |
GRE Physics
Start Test
Study First
Subjects
:
gre
,
science
,
physics
Instructions:
Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can
study here
.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.
This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. Resonance frequency of LC circuit
Dp/dt = L / (t ?V)
1/vLC
?? = h/mc * (1-cos(?))
U - ts = -tlog(Z)
2. Volumetric Expansion
E ~ (1/(n_f)² - 1/(n_i)²) ~ 1/?
V = V0 + V0 a ?T
C_eq = ?C_i
Q = CVexp(-t/RC)
3. EM: Maxwell'S equations
E = <?| H |?>
div(E) = ?/e_0 - curl(E) = der(B)/der(t) - div(B) = 0 - curl(B) = µ_0J + µ_0e_0*der(E)/der(t)
W' = (w-v)/(1-w v/c^2) ; observer in S sees an object moving at velocity w; another frame S' moves at v wrt S.
Series: 1/k_eq = 1/k_1 + 1/k_2; Parallel: k_eq = k_1 + k_2
4. Rayleigh'S Criterion
Sin(?) = ?/d
(° of Freedom)kT/2
E = <?| H |?>
P(s) = (1/Z) Exp[-E(s)/(k T)] Z = S_s(Exp[-E(s)/(k T)])
5. Coriolis Force
F = -2*m(? x r)
X_L = i?L
E = <?| H |?>
I_z = I_x + I_y (think hoop symmetry)
6. Thermo: Monatomic gas ?=?
? = 5/3
Opposing charge induced upon conductor
DW/dq
PdV +dU
7. Quant: [L_x -L_y] = ?
Infinitely close to equilibrium at all times
ih_barL_z
(° of Freedom)kT/2
P/A = s T^4
8. Helmholtz Free Energy
W' = (w-v)/(1-w v/c^2) ; observer in S sees an object moving at velocity w; another frame S' moves at v wrt S.
U - ts = -tlog(Z)
C_eq = ?C_i
Hbar*?³/(p²c³exp(hbar?/t)-1)
9. Ohm'S Law w/ current density
Q = CVexp(-t/RC)
A[B -C] = A[B -C]+[B -A]C [A -B] = -[B -A]
F = µ0 q v I / 2pr
J = E s - s = Conductivity - E = Electric field
10. Lab: Precision of Measurements
F = mv²/r
Measurements close to mean
X_L = X_C or X_total = 0
Z_c = -i/(?C) ; Z_L = i ? L
11. Springs in series/parallel
E = s/e_0
Sin(?) = ?/d
Cos[?] Sin[?] -Sin[?] Cos[?]
Series: 1/k_eq = 1/k_1 + 1/k_2; Parallel: k_eq = k_1 + k_2
12. Parallel axis theorem
I = I_cm + (1/2)m d^2
Measurements close to mean
Always Real
µ0 I1I2 / (2pd)
13. Force/length between two wires
µ0 I1I2 / (2pd)
Triplet: symmetric - net spin 1 Singlet: antisymmetric - net spin 0
?s = 0 - ?l = ±1
.5 LI²
14. Single Slit Diffraction Maximum
H = H_0 + ?H
Let w_i = 1/s_i^2;x_wav = S(w_i x_i) / Sw_i - s_xwav = 1/Sw_i
0
Asin(?) = m?
15. Thermo: Adiabatic Work vs Isothermal Work
W_A < W_I
Product ( nj ^ vj ) = Product(nqj ^ vj exp (-vj F(int)/Tau))
div(E) = ?/e_0 - curl(E) = der(B)/der(t) - div(B) = 0 - curl(B) = µ_0J + µ_0e_0*der(E)/der(t)
Q = CVexp(-t/RC)
16. First law of thermodynamics (explain direction of energy for each term)
E = Vmin : circle - E = 0 : parabola - E<0 : el - E>0 : h
Q = U + W Q = heat in system - U = total energy in system - W = work done by gas
DW = P dV
C_eq = ?C_i
17. Quant: Expectation Value
<?|O|?>
? = 5/3
E = s/e_0
Z_c = -i/(?C) ; Z_L = i ? L
18. Atom: Bohr Theory Ionization
V(r) + L²2/2mr²
E = Z²*E1
DB = ( µ_0 I/(4Pi) ) dl(cross)rhat/r^2
I = Im (sinc²(a)) ; a = pai sin(?) / ?
19. Solid: Resistivity of Semi-Conductor
?~1/T
Faraday/Lenz: current inducted opposes the changing field
Cos[?] Sin[?] -Sin[?] Cos[?]
ds² = (c*dt)² - ?(x_i)²
20. Planck Radiation Law
N d flux / dt
M? = 2dsin(?)
I = I_cm + md²
Hbar*?³/(p²c³exp(hbar?/t)-1)
21. Rocket Equation
Hbar*?³/(p²c³exp(hbar?/t)-1)
Dv = -udm/m - v = v0 + u ln(m0/m)
I = Im (sinc²(a)) ; a = pai sin(?) / ?
F = R/2
22. Thermo: Partition Function
Z = ?g_i*exp(-E/kT)
?s = 0 - ?l = ±1
In Zeeman effect - the contribution of electron spin to total angular momentum means that it isn'T always three lines and they are not always equally spaced.
L = T - V dL/dq = d/dt dL/dqdot
23. Internal Energy of an Ideal Gas
µ = Current * Area T = µ x B
(3/2) n R ?t
P = µ_0 q^2 a^2/(6Pi c); No radiation along the axis of acceleration
Measurements close to mean
24. Solid: Resistivity of Metal
When you apply a uniform electric field - it induces a dipole moment and interacts with it - and that effect depends on |mj |. So if j is an integer - splits (asymmetrically) into j+1 levels - and if j is a half integer - splits (asymmetrically) into
?~T
F = R/2
Triplet: symmetric - net spin 1 Singlet: antisymmetric - net spin 0
25. Stefan-Boltzmann law for blackbodies (power per area and T)
<T> = 1/2 * <dV/dx>
P/A = s T^4
A[B -C] = A[B -C]+[B -A]C [A -B] = -[B -A]
µ = Current * Area T = µ x B
26. Astro: Kepler'S Third Law
P² ~ R³
1. Heat is energy 2. Entropy never decreases 3. Entropy approaches a constant value as t -> 0...
qvb = mv²/R
E = Vmin : circle - E = 0 : parabola - E<0 : el - E>0 : h
27. Work in a capacitor
E²-p²c²
1/2 CV²
<T> = -<V>/2
L^2 |E - scl - m> = hbar^2 scl(scl+1) |E -scl -m> L_z |E - scl - m> = hbar m |E - scl - m>
28. 3 Laws of Thermo
1. Heat is energy 2. Entropy never decreases 3. Entropy approaches a constant value as t -> 0...
<?|O|?>
Triplet: symmetric - net spin 1 Singlet: antisymmetric - net spin 0
F = I L X B
29. Thermo: Blackbody Radiation
(3/2) n R ?t
ma + kx = 0
E = <?| H |?>
F = s * T4
30. EM: AC Resonance
Z_C + Z_L = 0. Occurs when ?=1/Sqrt[L C]
F = R/2
X_L = X_C or X_total = 0
Measurements close to mean
31. Energy in Inductor
.5 LI²
Cv = dE/dT = 3R
H = T + V;qdot_i = dH/dp_i - pdot_i = dH/dq_i
µ = m_e/2
32. Thermo: 1st Law
L = µ N² A / l : N = number of turns - A = cross sectional area -l = length
Dv = -udm/m - v = v0 + u ln(m0/m)
?L/A - L = length - A = cross sectional area - rho is electrical resistivity
dQ = dW +dU
33. Lab: Accuracy of Measurements
I = I_cm + md²
(3/2) n R ?t
Measurements close to true value
E = Vmin : circle - E = 0 : parabola - E<0 : el - E>0 : h
34. Force exerted on charge by long wire
F = µ0 q v I / 2pr
1s² - 2s² 2p6 - 3s² 3p6 3d¹°
L = µ N² A / l : N = number of turns - A = cross sectional area -l = length
N d flux / dt
35. Boltzmann / Canonical distribution
ma + kx = 0
Dv = -udm/m - v = v0 + u ln(m0/m)
P(s) = (1/Z) Exp[-E(s)/(k T)] Z = S_s(Exp[-E(s)/(k T)])
DB = ( µ_0 I/(4Pi) ) dl(cross)rhat/r^2
36. Bernoulli Equation
L = mr²d?/dt
P +1/2 ? v² + ?gh = Constant
µ0 I1I2 / (2pd)
C_eq = ?C_i
37. EM: Method of Images
E ~ (1/(n_f)² - 1/(n_i)²) ~ 1/?
Exponential - E = -ma²/2hbar² - a is strength of delta wellt
Opposing charge induced upon conductor
N d flux / dt
38. Lensmaker Equation - Thin Lens
Asin(?) = m?
I = I_cm + (1/2)m d^2
ma + kx = 0
1/f = (n-1)(1/R1 - 1/R2) if both positive - they are convex - concave
39. SR: Spacetime Interval
ds² = (c*dt)² - ?(x_i)²
4H + 2e- ? He +2? + 6?
? = ?0 root((1-v/c)/(1+v/c))
V(r) + L²2/2mr²
40. Wein'S Displacement Law
Z²/n² (m_red/m_elec)
µ0 I / 2R
? = h/mv
?max = 2.898 x 10 -³ / T
41. Focal point of mirrror with curvature
µ = Current * Area T = µ x B
E = s/e_0
F = R/2
?mv
42. Invariant Energy Quantity
(3/2) n R ?t
E²-p²c²
1/2 CV²
Isentropic
43. Hamiltonian and Hamilton'S equations
H = T + V;qdot_i = dH/dp_i - pdot_i = dH/dq_i
C = 4pe0 ab/(a-b) = inner and outer radii
E = <?| H |?>
Let w_i = 1/s_i^2;x_wav = S(w_i x_i) / Sw_i - s_xwav = 1/Sw_i
44. Selection rules for atomic transitions
? = h/mv
1/vLC
?scl = +/-1;?m = 0 - +/-1;?S_tot = 0;(?j = ?scl + ?S_tot)
1/2 CV²
45. Current in resistor in RC circuit
Dv = -udm/m - v = v0 + u ln(m0/m)
W' = (w-v)/(1-w v/c^2) ; observer in S sees an object moving at velocity w; another frame S' moves at v wrt S.
E = <?| H |?>
I = V/R exp(-t/RC)
46. Magnetic Dipole Moment and Torque
F = R/2
?? = h/mc * (1-cos(?))
<?|O|?>
µ = Current * Area T = µ x B
47. Radiation (Larmor - and another neat fact)
4H + 2e- ? He +2? + 6?
Const: 2t = (n +.5)? Destructive 2t = n?
?max = 2.898 x 10 -³ / T
P = µ_0 q^2 a^2/(6Pi c); No radiation along the axis of acceleration
48. QM: de Broglie Wavelength
S = (hbar/2) s ;with S = S_x xhat + S_y yhat + S_z zhat -s = s_x xhat + s_y yhat + s_z zhat
?= h/v(2mE)
U = t^2 d/dt (logZ)
Opposing charge induced upon conductor
49. Invariant spatial quantity
L = T - V dL/dq = d/dt dL/dqdot
I = Im (sinc²(a)) ; a = pai sin(?) / ?
Ct²-x²-y²-z²
Product ( nj ^ vj ) = Product(nqj ^ vj exp (-vj F(int)/Tau))
50. De Broglie wavelength
IR + Ldi/dt = 0 - I = I0e(-tL/R) Work = 1/2 L I0^2
I = I_cm + md²
1/vLC
? = h/p