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1. if an energy intensity of 2000 W is exerted by a spherical source, what will

ID: 3901769 • Letter: 1

Question

1. if an energy intensity of 2000 W is exerted by a spherical source, what will be its average power output at a distance of 12 m from it?

a. 3.1 W/m^2    b. 1.1 W/m^2       c. 2.1 W/m^2         d. 4.1 W/m^2


2. a radioactive sample has a half-life of 2.5 min. what fraction of the sample is left after 40 min?

a. 1/256     b. 1/40         c. 1/16        d. 1/8


3. an atom has 8 protons and 17 nucleons. if it undergoes beta - decay, what are the number of protons and neutrons, respectively, in the daugher nucleus?

a. 7,16        b. 8,18        c. 9,17         d. 8,17

Explanation / Answer

1.     1.1 W/m^2   (apply I = power/areA)


2. c. 1/16  


3. DUYRING BETA DECAY, aTOMIV INCREASES BY 1 UNIT AND MASS NO. REMAINS SAME

SO c. 9,17