Related Questions

Why does the ionosphere of the Earth's atmosphere facilitate radio communication? i. The presence of ozone causes the reflection of radio waves to earth ii. Radio waves have a very long wavelength
A i only
B ii only
C both i & ii
D neither i nor ii
A paragraph must have____
A an object
B a single idea or topic
C topics
D more than one para
Which layer of the earth's atmosphere reflect back the radio waves to the earth's surface ?
A Ionosphere
B Stratosphere
C Mesosphere
D Exosphere
দুটি সুসঙ্গত উৎস থেকে λ দৈর্ঘ্যের দুটি তরঙ্গ সমদশায় বের হয় । একটি বিন্দুতে যেখানে তরঙ্গ দুটি মিলিত হয় সেখানে তাদের দশা পার্থক্য 90° । তরঙ্গ দুটির অতিক্রান্ত পথ পার্থক্য তখন কত ? ( Two coherent sources emit waves of wavelength λ which are in phase. which are in phase. The two waves meet at a point where they have a phase difference of 90°. Which of the following could be the traversed path difference between the waves?)
A 2λ
B λ
C λ/2
D λ/4
Fill up the blank with appropriate word: A good teacher discovers the treasure hidden _ each student.
A inside
B in
C within
D with
A train is travelling at 100 km per hour (Kmh) overtakes a motorbike travelling at a speed of 65 kmh in 40 seconds . What is the length of the train in meters?
A 400
B 450
C 500
D Try your self
A train travelling at 100 km per hour overtakes motorbike travelling at a speed of 65 km per hour in 40 seconds. What is the length of the train in meters
A 400 metrs
B 450 meters
C 500 meters
D 550 meters
Which of the following statements is correct about sound waves and light waves?
A Both transverse waves
B Both longitudinal waves
C Sound waves are transverse waves and light waves are longitudinal waves
D Sound waves are longitudinal and light waves are transverse waves
Which of the following reflects radio waves back to the Earth?
A Ionosphere
B Thermosphere
C Tropopause
D Mesopause
পৃথিবী পৃষ্ঠে একটি ইটের ওজন 81 N. পৃথিবীর অর্ধেক বাসার্ধের সমান উচ্চতায় এবং অর্ধেক বাসার্ধের সমান গভীরতায় ইউটির উপরে পৃথিবীর অভিকর্ষ বলের মান কত হবে?(A brick weighs 81 N on the surface of the earth. What are the earth's gravitational forces act on it at a height of half of the radius of the earth and at a depth of half of the radius of earth, respectively?)
A 36 N and 81 N
B 36 N and 40.5 N
C 36 N and 20.25 N
D 98 and 40.5 N
E 81 N and 81 N

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