A count rate meter shows a count of $240$ per minute from a given radioactive source. One hour later the meter shows a count rate of $30$ per minute. The half life of the source is:

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Answer 1

Since in radioactive decay, the decay rate is proportional to the amount of substance.
Hence, $\frac{2 4 0}{2 ^{N}} = 30$ , where N is number of half lives passed in one hour.
This gives, $N = 3$ .
Hence half life: $t_{1 / 2} = \frac{6 0}{3} m i n = 20 m i n$

Answer 2

Since in radioactive decay, the decay rate is proportional to the amount of substance.

Hence,

\frac{2 4 0}{2 ^{N}} = 30

, where N is number of half lives passed in one hour.

This gives,

N = 3

.

Hence half life:

t_{1 / 2} = \frac{6 0}{3} m i n = 20 m i n

A count rate meter shows a count of $240$ per minute from a given radioactive source. One hour later the meter shows a count rate of $30$ per minute. The half life of the source is:

$80 m i n$

$120 m i n$

$20 m i n$

$30 m i n$

Since in radioactive decay, the decay rate is proportional to the amount of substance.
Hence, $\frac{2 4 0}{2 ^{N}} = 30$ , where N is number of half lives passed in one hour.
This gives, $N = 3$ .
Hence half life: $t_{1 / 2} = \frac{6 0}{3} m i n = 20 m i n$

A freshly made radioactive sample gives a count rate of $8000$ counts per minute. After twenty days, it gives a count-rate of $500$ counts per minute. What is the half-life of the material?

A rate-meter measures the number of disintegrations per second from a radioactive source. It gives a count of $320$ counts per second. Ninety minutes later, it gives $40$ counts per second. The half life of the source is

Answer the question:
A radioactive source produces a count rate on a detector of $1600$ counts / s. After $32$ hours the count rate has fallen to $100$ counts/s.
Both count rates have been corrected for background radiation.
What is the half-life of the source ?

The activity of a radioactive sample is measured as $N_{0}$ counts per minute at $t = 0$ and $N_{0} / e$ counts per minute at $t = 5$ min. The time, (in minute) at which the activity reduces to half its value, is :

A piece of bone from an archaeological site is found to give a count rate of $15$ counts per minute. A similar sample of fresh bone gives a count rate of $19$ counts per minute. Calculate the age of the specimen. Given $T_{1 / 2} = 5570 y e a r s$

Revise with Concepts

Discovery of Radiation

Introduction to Radioactivity

Alpha, Beta and Gamma Emission

Differentiate Between Alpha, Beta and Gamma Radiations

Background Radiations

A count rate meter shows a count of 240 per minute from a given radioactive source. One hour later the meter shows a count rate of 30 per minute. The half life of the source is:

80 min

120 min

20 min

30 min

Since in radioactive decay, the decay rate is proportional to the amount of substance. Hence, 2N240​=30, where N is number of half lives passed in one hour. This gives, N=3. Hence half life: t1/2​=360​min=20 min

A freshly made radioactive sample gives a count rate of 8000 counts per minute. After twenty days, it gives a count-rate of 500 counts per minute. What is the half-life of the material?

A rate-meter measures the number of disintegrations per second from a radioactive source. It gives a count of 320 counts per second. Ninety minutes later, it gives 40 counts per second. The half life of the source is

Answer the question: A radioactive source produces a count rate on a detector of 1600 counts / s. After 32 hours the count rate has fallen to 100 counts/s. Both count rates have been corrected for background radiation. What is the half-life of the source ?

The activity of a radioactive sample is measured as N0​ counts per minute at t=0 and N0​/e counts per minute at t=5 min. The time, (in minute) at which the activity reduces to half its value, is :

A piece of bone from an archaeological site is found to give a count rate of 15 counts per minute. A similar sample of fresh bone gives a count rate of 19 counts per minute. Calculate the age of the specimen. Given T1/2​=5570 years

Revise with Concepts

Discovery of Radiation

Introduction to Radioactivity

Alpha, Beta and Gamma Emission

Differentiate Between Alpha, Beta and Gamma Radiations

Background Radiations

A count rate meter shows a count of $240$ per minute from a given radioactive source. One hour later the meter shows a count rate of $30$ per minute. The half life of the source is:

$80 m i n$

$120 m i n$

$20 m i n$

$30 m i n$

Since in radioactive decay, the decay rate is proportional to the amount of substance.
Hence, $\frac{2 4 0}{2 ^{N}} = 30$ , where N is number of half lives passed in one hour.
This gives, $N = 3$ .
Hence half life: $t_{1 / 2} = \frac{6 0}{3} m i n = 20 m i n$

A freshly made radioactive sample gives a count rate of $8000$ counts per minute. After twenty days, it gives a count-rate of $500$ counts per minute. What is the half-life of the material?

A rate-meter measures the number of disintegrations per second from a radioactive source. It gives a count of $320$ counts per second. Ninety minutes later, it gives $40$ counts per second. The half life of the source is

Answer the question:
A radioactive source produces a count rate on a detector of $1600$ counts / s. After $32$ hours the count rate has fallen to $100$ counts/s.
Both count rates have been corrected for background radiation.
What is the half-life of the source ?

The activity of a radioactive sample is measured as $N_{0}$ counts per minute at $t = 0$ and $N_{0} / e$ counts per minute at $t = 5$ min. The time, (in minute) at which the activity reduces to half its value, is :

A piece of bone from an archaeological site is found to give a count rate of $15$ counts per minute. A similar sample of fresh bone gives a count rate of $19$ counts per minute. Calculate the age of the specimen. Given $T_{1 / 2} = 5570 y e a r s$