Learn Hardcore Greek: Ρυθμίζω την ένταση στην τηλεόραση κάθε βράδυ. - I adjust the volume on the TV every evening.

ρυθμίζω ends in -ω, which tells us it is 1st person singular → I.
So εγώ ρυθμίζω την ένταση… would be understood as I adjust the volume…, but the εγώ is normally omitted unless you want to emphasize I (as in I do it, not someone else).

So the sentence automatically means I adjust the volume on the TV every evening without needing εγώ.

What tense and person is ρυθμίζω, and what basic forms should I know?

ρυθμίζω is:

Present tense
Active voice
1st person singular
Imperfective aspect (ongoing / repeated action)

Some key forms:

(εγώ) ρυθμίζω = I adjust / I am adjusting
(εσύ) ρυθμίζεις = you (sg) adjust
(αυτός/αυτή/αυτό) ρυθμίζει = he/she/it adjusts
(εμείς) ρυθμίζουμε = we adjust
(εσείς) ρυθμίζετε = you (pl/formal) adjust
(αυτοί/αυτές/αυτά) ρυθμίζουν(ε) = they adjust

Past and future (just for recognition):

ρύθμισα = I adjusted (simple past, aorist)
θα ρυθμίσω = I will adjust (simple future)

In this sentence the present tense expresses a habitual action: something you do regularly.

Why is it την ένταση and not η ένταση?

Because η ένταση is nominative (subject form), and here ένταση is the object of the verb, so it must be in the accusative case:

η ένταση = nominative (subject) → The volume is high. = Η ένταση είναι ψηλά.
την ένταση = accusative (object) → I adjust the volume. = Ρυθμίζω την ένταση.

So after a transitive verb like ρυθμίζω, you use την ένταση (accusative), not η ένταση.

Why do we use the article την with ένταση, but there is no article before βράδυ?

Two different reasons:

την ένταση
- ένταση is a specific, known thing here: the volume (of the TV).
- Greek usually uses the definite article (την) in such cases:
  - ρυθμίζω την ένταση = I adjust the volume.
κάθε βράδυ
- κάθε = every/each.
- After κάθε, you do not use an article:
  - κάθε βράδυ (not το κάθε βράδυ) = every evening
  - κάθε μέρα, κάθε μήνα, κάθε χρόνο, etc.

So: article with ένταση because it’s a specific object; no article with βράδυ because κάθε already plays that role.

What exactly is στην in στην τηλεόραση?

στην is a combination:

σε (preposition in / on / at / to)
την (feminine singular accusative article the)
→ στην

So:

σε + την τηλεόραση → στην τηλεόραση = on the TV / at the TV

In modern Greek, σε + article almost always merges:

σε + τον → στον (masc.)
σε + την → στην (fem.)
σε + το → στο (neut.)

Why do we say στην τηλεόραση instead of just την τηλεόραση?

Because τηλεόραση is not the direct object here; it’s a location / surface: the place where you adjust the volume.

ρυθμίζω την ένταση → I adjust the volume (direct object)
στην τηλεόραση → on the TV (prepositional phrase with σε)

If you said only ρυθμίζω την τηλεόραση, that would mean I adjust the TV (itself) — e.g. its settings in general, not specifically the volume on it.

So:

ρυθμίζω την ένταση = I adjust the volume (object)
στην τηλεόραση = on the TV (where you adjust it)

Could I move κάθε βράδυ to the beginning of the sentence? Does the meaning change?

Yes, you can move it:

Ρυθμίζω την ένταση στην τηλεόραση κάθε βράδυ.
Κάθε βράδυ ρυθμίζω την ένταση στην τηλεόραση.

Both mean the same thing: you do this every evening.

Putting κάθε βράδυ at the beginning just emphasizes the time a bit more, but it doesn’t change the basic meaning. Greek word order is quite flexible, especially with time expressions like κάθε βράδυ, σήμερα, αύριο.

What does ένταση normally mean? Is it specifically “volume” here?

ένταση is a general word meaning things like:

intensity
strength
tension
loudness / volume (of sound)

In the context of a TV or radio, η ένταση almost always means the volume (how loud it is).

So in this sentence, την ένταση is naturally understood as the volume of the TV.

What gender is τηλεόραση and how is it declined?

τηλεόραση is feminine.

Singular:

Nominative (subject): η τηλεόραση = the TV
Accusative (object / after σε): την τηλεόραση = the TV
Genitive: της τηλεόρασης = of the TV

So in στην τηλεόραση, you have:

στην = σε + την (preposition + fem. article)
τηλεόραση in the accusative after σε

Does Greek present tense here mean “I adjust” or “I am adjusting”?

The Greek present (ρυθμίζω) covers both English forms:

I adjust the volume on the TV every evening. (habit)
I am adjusting the volume on the TV (right now). (current action)

In this sentence, the phrase κάθε βράδυ makes it clear that it is a habitual action, so the most natural English is:

I adjust the volume on the TV every evening.

But grammatically, the Greek present itself is broad enough to include both simple and continuous meanings; context decides which one is meant.