Question

7. a) Find the rate of energy flow through a copper block of cross-sectional area 15 cm and length 8.0 cm when a temperature difference of 30°C is established across the block. Repeat the calculation, assuming that the material is (b) a block of wood with the given dimensions. kcopper - 397 J/s.m. C, ker = 0.1397 Jls.m. C 8. Describe the change in the magnetic field in the space enclosed by a solenoid carrying a steady current lif (a) The length of the solenoid is doubled, but the number of turns remains the same, and (b) The number of turns is doubled, but the length remains the same. 9. An electron is moving at a speed of 1.0 x 10^ m/s in a circular path of radius of 2.0 cm inside a solenoid. The magnetic field of the solenoid is perpendicular to the plane of the electron's path. Find (a) The strength of the magnetic field inside the solenoid and (b) The current in the solenoid if it has 25 turns per centimeter. me = 9.11 x 109kg, 9 = 1.609 x 10", 40 = 41 X 10°C.m/A 10. Find the flux of the Earth's magnetic field of magnitude 5x 10ºT through a square loop of area 20.0 cm when: (a) The field is perpendicular to the plane of the loop, (b) The field makes a 30.0° angle with the normal to the plane of the loop, and (c) The field makes a 90.0° angle with the normal to the plane. 11. Starting from rest, a ball of 50cm radius rolls down a hill at a point 80cm below its starting point. How fast is it rotating at that point? Use I = mrº; v= : oor

Answer 1

Given: temperature cuffieron (T.-T.) -30° Long sth of block b = 8cm = 0.08m Cross-section area A=15cm² = 154104 m2 = 397 T/s.mºc et Rate of everyy flow do d.al KAIT -Ta ) thromal conduetruity Koffer fimular It = ? dt L lco bypor ! 397X15X10 44,30 0.08 2233125 x 10-4 223.31 J/sec reate of energy flow for copper = 223.81 J/ ct wood Karool A (T,-To) L 0.1397 x 15x10-44.30 0.08 785.8 x 10-4 dt ہء وحی 0.07858 J/g grow

(8) mayne the field in die lenoid B = Moni 2020/5/18 20 Mond IMM of turns N no ܝܐ Length (a): [ -> 24. NON Mo Ni 3. thoni 2 BOB 2 e Nossame), shenu if length of so honord is doubled magnetic field will be half b) 4-4, N-2N Mo ani B = 2B 2 B2B but L - L if turns is dauphed, Argo but L magnetic field will be doubled.

Gia vt speed of electron - 1.0x10km/s 2020/5/18 20 radius r= 2.0cm = 0.02 m @ formarla qVB = m02 B = mo ar hore me mass of electron = 9.1830-01 ng q charge of ee 1-641019 C B = POISO1,641049 X 0,02 0,1X10-31 x 1.08104 = 284.374 X10-8 2.843 410-6 Testa-

A Вазо A=20x104m² В -, - BA (os ao B = 's X). 2 o-864 X 10-1 = d.co-BT- ma ( 9 = 90° д 4. = BA Cos 90 Внхо

angh= 3 mua v=fagh Giren: h=80cm = 0.8m, radius f=50m = 0.5 m 2= g = 10 m/s Jagh Saxlox0.80 v=√16 = 4 m/5 v=rw angular welouty zie u 0.5 =8 rew/sec do 2020/5/18 21:08 honce votuhiy sbeed is & rool, see