Answer:
(a) Eₐ = 6.36 J/s
(b) Eₐ = 4.64 J/s
Explanation:
Stefan-Boltzmann law: States that the total energy per second radiated or absorbed by a black body is directly proportional to the absolute temperature.
Using, Stefan-Boltzmann equation
Eₐ =eσAT⁴ ................ Equation 1
where Eₐ = Radiant energy absorbed per seconds, e = emissivity, σ = stefan - boltzman constant, A = Surface area. and T = temperature in kelvin
(a) Where e = 0.89, σ = 5.67 ×10⁻⁸ watt/m²/K⁴, A = 140 cm² = 140 cm²(m²/10000cm²) = 0.014 m², T = 35 °C = (35 + 273) K = 308 K.
Applying these values in equation 1 above,
Eₐ = 0.89 × 5.67 ×10⁻⁸ × 0.014 × (308)⁴
Eₐ =6.36 J/s
(b) when e = 0.65,
∴ Eₐ = 0.65 × 5.67 × 10⁻⁸ × 0.014 × (308)⁴
Eₐ = 4.64 J/s
Question:
Mateo drew the field lines around the ends of two bar magnets but forgot to label the direction of the lines with arrows. In which direction should an arrow at position 1 point?
left
right
up
down
Answer:
The correct answer is
Left
Explanation:
Magnetic circuits describe the path of a magnetic flux. In the same way electricity follows a complete closed circuit, the path of a magnetic flux is also a complete and closed circuit which leaves from the N pole, migrates through the air and reenters the magnet through the S pole through which it passes back into the magnet to come to the N pole again.
As such the magnetic field lines emanate from the N pole which is on he right to the S pole which is on the left. Hence the arrow should point in the left direction.
Answer:
e. Doubles.
Explanation:
Resolving power is given by the formula as follows :
Here, 
is the angle subtended by two distant objects
D is diameter of the telescope
Here, the diameter of a radar dish is doubled, assuming all other factors remain unchanged, then the resolving power gets doubled. Hence, the correct option is (e).
Answer:
A). σ = 3.823 x 
/N-
B). 
C/
C). 
J
Explanation:
A). We know magnitude of charge per unit area for a conducting plate is given by
where, E is resultant electric field = 1.2 x 
V/m
is permittivity of free space = 8.85 x 
/N-
k is dielectric constant = 3.6
∴
= 3.6 x 8.85 x x 1.2 x
= 3.823 x /N-
B).Now we know that the magnitude of charge per unit area on the surface of the dielectric plate is given by
C/
C).
Area of the plate, A = 2.5 
= 2.5 x 
diameter of the plate, d = 1.8 mm
= 1800 m
∴ Total energy stored in the capacitor
J
